Um I am not so sure about plenty of money thing. I think more accurately, if one had an excess of say, 200-300K cash flow (profit) a year guaranteed, it would be like sim.
Once you make a bunch, the issue is cash flow-generation and capital preservation. A bad martingale loss would set one back pretty hard loosing what you have made, which is almost worse.
An old school (Pre-5 rings- Musashi), is that you need to be so proficient it is deeply burned into you mind and body, that the right thing is second nature. Of course it was hard to keep your cool with 50+ guys with swords, spears and bow-arrows on a battlefield. So trading should be easy right?
Also sometimes it is more about being right or wrong than making money. We have all been there.
Of course - plenty of money on it's own is NOT going to help. Just like psychological work can NOT replace the lack of trading skills/experience.
One of the richest men in Norway at the time who had retired after selling a tech company got bored in retirement and started day trading stocks being one the biggest single players in the stock markets at the time. Ended up losing his entire fortune and even ended up in debt.
Personally, I'm not very well funded, but my trading account is almost doubled after funding it and there's no doubt a big difference between trading from that place with a cushion of profits compared to being in deeper drawdown and a few bad trades from a margin call (been in that place, too).
