Hey guys,
If the plan pre is to simply setmine, then do we HAVE to fold when we don't hit our set?
I feel like if we don't, then we're defeating the purpose of making all of our setmining pots cheap, therefore making it less profitable in the long run.
Am I right?

if you're setmining then try to see the flop as cheaply as possible.
post-flop if you think your hand is good just stick with it. it is usually a couple bb difference at the final pot so it doesn't matter THAT much.

you're losing more money than you make when you inflate the pot pre-flop when your goal is to setmine and when you miss stick with your hand as that depends on the board

If you are set mining then folding if missed is the usual play. Like most things you can change the plan as the hand unfolds but you have to be very careful.
A lot always depends on how deep you are, how much you have to call and a few other factors.
If in tournies especially SnGs you typically only set mine in the first level or two as the implied odds really fade fast as the blinds go up, bigger stacked/field tournies are different.
Try to set mine when you are deep and have a good chance of getting well paid, for eg, it's better to be up against the utg player than a Btn open as there is a good chance the Btn is just stealing and will just fold the hand when you hit but the utg probably likes his hand.

Set mining is often a way to bleed money for many beginning players. Set mining when 100bb deep is profitable if one or more of the following conditions are met:
1) vil will stack off if you hit and they have a 1-pair type hand
2) you will occassionally make a move with your small pocket pair

There is no point trying to set mine 100bb deep against a good LAG type player if you will fold any time you miss as their range is not strong enough to pay you off often enough if you hit and they will double barrel too often for you to be able to call down your small pair profitably. This is extra bad against strong hand readers who can see if you never semi-bluff your strong draws and so they can put you on exclusively a set when the flop comes 8 7 5 and you raise. Folding AA is trivially easy there against many TAGfish.

Set mining is very profitable against very tight players who will stack off with their overpair - there are a lot more moderate to strong hands in their range that they will be willing to get it in with when you hit. Same goes for loose whales who think top pair is the nuts.