Problem with your statement is that you could make more trading the "easy" way for a few years, then have the highest quality of life possible. Why would your quality of life suffer since you said it's the easier way to trade? My guess is you really haven't figured out how to actually trade very short term but you think it might be easier. In fact I find short term movements more abrupt since all it takes is one player in the market who needs to unload his shares fast and that will pull down the market. If he unloaded the same amount over a longer time, he would impact the market much less.
In which case one could also argue that if after years you are still finding it hard, then perhaps you need to look for other means of making speculative bets. Obviously you don't trust yourself nor your method.
Tell me where we will be in 15 seconds and also where will we be in 1 hour. The margin for error on 1 hour will be much bigger than the one on 15 seconds. So 15 seconds is easier. The way somebody trades depends of a lot of things: personality, trading system, volume.... If you want to trade size you cannot trade very short periods. So I have to trade longer periods. I trade what for me is the optimal timeframe in relation to my size. Of course the best would be to trade 1 sec and take 20 points profit on 1000 contracts, but.... I gave comments here because Schizo is jumping around doing dozens of trades for almost no profit (if there is already profit). I went long short after the opening. 1 trade for almost 10 points and very relax trading, no jumping around, I even walk around in my house and don't have to be in front of my screens all the time.