Of course it's impossible to answer the question "how much will my income be?" but what is maybe even more important to me is how reliable can a poker side income be?
After some years of study and playing solid, stopping when on tilt and going for the long run playing stakes which are comfortable to play.
Of course it's never good to be dependant on the income, but how steady is it? Is it common to have frequently a month with significant loss? I have no clue, but I'm asking you guys with decades of experience ;D

It depends on what you're playing (cash? tourney? NLHE? PLO?) and your edge at your stakes. The answer can range from, "Almost never a losing month" to losing most months.

Cash game NLHE, and yeah edge at stakes is hard to say, it's a kinda "future question", but I think grinding and studying until you're comfortable at some stake and stay with that because you feel like you're most profitable there.

Oh and throw in #tables you play as another variable (since I also don't know if you're talking live or online).

Cash game profit can be pretty steady.

Oh yeah always 3 tables at Pokerstars right now so that I can keep sight at all 3 if them (fits the screen) and so that I always have time to think and keep track of players, but that could grow in the future when play is more automatised and with double screen etc.

Variance is the big variable. In other words you can be running like God one month and hit a big downswing the next month. There is no reliability of profit in poker. The long run is measured in years not months.

I pay myself per hand player so I never have a losing month as far as cashing out goes.

I pay myself half my winrate x hands played.

i don’t include potential cash out money in my bankroll when deciding what limit I’m rolled for.

Edit in bold.

Rewarding myself per hand also adds an incentive to get more hands in. Win or lose I’m able to show something for my play while still investing money into moving up or maintaining limits. Downswings still happen, but it doesn’t sting as bad when I’m still getting paid.

This allows me to also keep cashing out when I hit the apex of which limit my skill will let me play at.

Poker income is subject to massive amounts of variance. Losing months are not uncommon among cash regs. For MTT players, losing years are possible, or even likely.

A secure job (e.g. schoolteaching) usually pays a fixed monthly wage on an annual contract. Other jobs pay an hourly wage and your contract might be on a rolling 3-month basis. Poker is more like a piecework job in the "gig economy", where you have no job security, and your income will fluctuate based largely on being in the right place at the right time. Your bankroll changes size not at the end of the month, week, or even hour. It alters every time you play a hand.

1) The 'opportunity' to play poker seems to be surviving just fine. Even in the US the online scene is steadily coming back to life .. as are the 'secret' group Apps that are growing by storm the last months or so.

2) Other than perhaps being replaced, you don't have to worry about 'your customers' becoming smarter than you are in a normal job. The more you play, the more they may know about you, which will affect your income.

3) Playing as an enjoyable successful hobby is way different than plugging it into a monthly/annual budget as a reliable component. GL

To give you an idea of variance, I'll tell you about a bankroll building project that I started, on Juicy Stakes Poker, on 1/1/2017. I had $40 that had been sitting there for two years and I didn't want to deposit to add to that. My goal was to grind it up to $500 by the end of the year.

I wanted to do this with strict bankroll management, having 100-buy-ins at whatever level I was playing. I don't multitable, so I starting grinding away, playing online $1 MTTs (SNGs almost never run on that site) and I played only $1 MTTs until I was over $300.

At the end of the year I had $480.

It was a great experience. I play mostly live. I understood the math of what "long-term" means in poker, but experiencing it is different. I had three losing months. It was not fun losing more than $50 in a month--that was more than 10% of my goal down the drain. 450 tournaments was enough to get an idea of what variance is like and how bad downswings can be.

The other great thing about it was that I could work on my game and see the results in real time. When I was working on something new, or trying to get better at something (continuation betting was a weak area that I worked pretty hard) 50 tournaments concentrating on one thing gave me a pretty good idea when something was working and when it wasn't. I could never get that kind of feedback playing 10-20 MTTs a year.

Finally, it was a great exercise in discipline and determination. It was my job to play every single day, 7 days a week. I missed a few days during the year, but only about 5.

When I was in the middle of a big downswing I stuck with it and played the next day whether I was up $80 for the month or down $50 for the week. When I had a great week or month I didn't take it for granted because I knew that the next downswing would be coming soon.

I'm sure that someone on here who plays 10 tournaments at a time could tell you some horror stories of losing thousands in a downswing, but I hope that my experience gives you at least some idea of what you can expect.

You need to open up more table, if you fit 3 in ur screen surely u can fit 4, but realisticly you would need 6 at least if NLHE.
Also nowadays it s much harder the it used to be to make straight forward profit, most of the regs rely on RB and ny playin only 3 table you wont be able to make enough of it, if u play on ps, close to 0
I understand you want to see the actions, but you shlould consider using some poker tools that helps with the history at the table like HEM or PT

Yeah I do use PT4, couldn't do without it.
And maybe doing more tables is worth a shot, only don't have the oppurtunity anymore, almost broke now. It went very well in the beginning, I made something like $10 profit before the graph of my last hands since I use PT:


https://imgur.com/a/CmYsipE

Now there's only 9 dollars left... No idea how this downswing could happen, I felt like I played really well; only better and better because I knew better how to play against the others and I had just analysed my play with the statistics and some hands... sigh.

If you are on a new site (to you) that allows HUDs....then as you play more and more, the regs get a better picture of your play. Up until then, most regs would be cautious. Maybe now you are getting a few more playing back at you....?