> you can learn from the things you experienced during that time

Of course you can learn from your experience, and the author did learn from his experience, which is the entire point of the tweet, so the author doesn't need to be told that he can learn from his experience. He already knows!

Nonetheless, the author considers his time to have been a waste.

> meaning it wouldn't be a waste

This does not follow.

> I worked in the cryptocurrency industry, sold drugs, interacted with gangs, and a bunch of other stuff but none of them broadly harmed society

Ok...

> One could surely argue that making "paid browser extensions" somehow have a net negative impact on the world, and if that was proven, would that mean all the time you spent on those sort of projects were suddenly wasteful and you should have realized this up front?

If that was proven? Well, prove it. Go ahead, make my day. Otherwise, this is just a silly piece of sophistry with no applicability.