When I sell coins to someone on an exchange there is no way to know if the price will go up or down
that is purposefully obtuse: you're complaining that there are too many asics and they're ruining the market, and you also claim that there's no way to know how the market will react? You're denying the obvious.
if you are looking at short-term ROI, you're making coins, dumping them, and abandoning the blockchain when you turn your hardware to another coin.
The difference is you are selling people hardware knowing that the person buying it is going to lose money.
that's not actually true e.g. how much do you pay for electricity?
what is your exit strategy when you buy hardware?
what is your investment strategy?
these factors all affect profitability as much or more than "what coin to mine".
you're assuming just becuase you can't turn a profit on asics, nobody can do it legitimately. i'm saying you really need to do your homework, and anticipate, rather than react, to the market.