Assalamu alaykum
I can't find the hadith which states ou rizq is ordained.
I agree that we have to work for it, somewhat like a raffle that you have to enter and then claim the prize. I don't believe there's anything wrong in reaching your potential and working hard to improve the ummrah financially, infact it's rewardable and every Muslim's duty.
I do, however, believe you're being very cold with respect to those who haven't been able to ''achieve'' financially (you mentioned something about ''the stupid mistakes of the poor.'') Some people do not have the capacity with which to earn a good living, or even a half-decent one, they can make the best from their situation but not necessarily succeed. Also, I wouldn't say that Allah swt was 'stingy' if certain individuals worked hard all their lives for nothing- for some it's a test and others a blessing.
Insha Allah khair, we're all accountable for our deeds and are only responsible for our own wealth and how we spend it.
