You won't even think about trading under pressure if you are learning to trade the right way. You cannot trade under pressure if you read trading books, have mentors, be a part of peer group of traders. The people who are likely to trade under pressure are those who are greedy and want to make it a get rich schemes. Trading for them is short term and not a long term endeavor.
I use to wonder why people always put themselves under pressure of any sort just because they want to get rich faster, moreover everything is a gradual process and so it needs time to pass through every stages but just like you said, greed has taken over them, it's just like gambling that many others want to get quick money from all because of selfish gains other than gambling with what they can afford to lose. And mostly they fail to understand what works for the next person may not actually work for them in most cases.