Regarding investing in altcoins, I don't see anything wrong with investing in them, although they may be riskier than bitcoin, their return will also be greater than bitcoin. Investing in altcoins is not too bad, but we should only invest when we are ready to take risks and have enough knowledge and experience to choose potential projects. Do not invest in them blindly and rely on luck like gambling, everything requires specific knowledge and planning.
Trading looks lucrative but its not very easy to tackle. I gave up trading long ago, it may be suitable for some but not for me. If you have to invest in alts then split your capital into two parts, major portion for bitcoin and minor for trading into alts. Price of alts is tightly coupled with Bitcoin so its best to invest in bitcoin as price of alts will only go up with Bitcoin. Take example for Eth for instance there is not even a single instance where Eth has gone up on its own. So better stick with Bitcoin.