If you are poor you have to go for it and trade all you can. You need the money. If you are "rich" (from trading), you don't have the pressure to make money anymore. On top of that you will have a lot of experience that enables you to reduce your trading to the most promising patterns or hours to trade. You can skip the "inactive" hours. Gives you plenty of time to enjoy life.
I think the two reasons for this are rather different. One being lower testosterone levels, being less competitive in general. Second is the stress from trading takes its toll, taking on high risks every day wreaks havoc on your health if doing it for many decades.
Yes it depends on the strategy. If you have a trending strategy for example, you would need to compare the strategy deployed during the same trending period. The span of each segment of the strategy should have a reasonable amount of trades to have statistical significance. If it doesn't have that many trades then lengthen the comparison span. eg. Quarterly to Biannual comparison.
Correct but money also changes u take two separate individuals young irr old but same age the one without money is usually moving faster