Right around 2005/6, the two guys who got me into poker were playing each other heads up at home just for practice. Their accounts were locked, but it made me wonder how online poker works, what security measures exist, and how many people might be cheating.

So even then, when I barely knew how to play, I wondered why two or more people don't start a telephone conference call to share info. (folded cards, reads, advice, etc.) It would give them an edge and there is nothing complicated about making a phone call to your friend(s).

I think the answer is that in 2008 people could learn some basic tips and beat the game and players focused on winning, not cheating. Grinders were willing to take shots because they knew they could always move down and rebuild quickly. There was no big incentive to cheat. There was enough money floating around to keep everyone happy. Even breakeven grinders could earn themselves a 120K SNE income.

Today, poker is not that easy. It's a lot easier to increase your winrate via cheating than any other means. After playing a few years and having no resume to get a real job, people are also desperate to hang on. Some people start coaching, training, vlogs, staking - and some people start cheating/scamming.

for sure, i have made way more cheating

There was for the mafia.
In online poker it goes all the way back to the UB scandal and the infamous 'ablackcar' multi account.
It has been known for people to make a lot of money legit though.