The same thing could be said about the early days of bitcoin, people were making nothing mining a "worthless" digital currency and look where it ended up. Same thing happens to a lot of new altcoins you just have to be willing to take the risk.
Bitcoin is unique, and now go find the difference between some new 10 projects for mining coins. The actual difference is only in the names of the coins, most of them will die even before they have time to develop somehow.
Yes, you are right.
I mining many coins, even if 1 out of 10 grows well in price, it will overlap all expenses, including mining the 9 coins that have died.
Risk diversification, do not mining one coin for too long, switch, distribute hashrate.