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.
Sometimes the market is highly volatile and as a trader we have to make a choice, like whether we should take risk to make more profit or take less risk to make less profit, in other words whatever the situation of market is, more risk means more profit and more lose and less risk means less profit and less lose so the choice is always of a trader.
If a trader is trading under pressure due to some factor, like financial lose, etc. that's his choice, but factors like, liquidating yourself all, and taking loan, and doing bad stuff to make some profit so that you would be back on track is one of the things that a trader should never do.