A shortened, abstract explanation of the bitterness is as follows:
If you set out to care and do the right thing, not being a saint but generally aiming for a decent goal in an honest way, people quickly chastise you for not playing by the rules. I never learnt to follow rules well, and don't particularly want to. Or rather, if I have to play by the rules that's the only thing I'm prepared to do. I'd then play the rules, and be as cynical and self-serving as possible in the process. I could also have done that sooner and been better off.
I don't know how to enjoy life while playing by the rules. Or rather, I don't know how to do things in good faith (which is necessary for life to be fulfilling) and by the rules (which seems to be necessary to get along) at the same time. It seems perhaps possible to not be bound by rules in a situation where you have almost no power, or enormous power, and neither of those exits seems very appealing at the moment.
At times like this I get a somewhat dim view of the Human Condition...