there is absolutely no guarantee of coins other than bitcoin. some of which always change in price and can't be said to be okay. I mean in the top 10 in the coinmarketcap it is good for investment but you also need to research first and not directly to buy it.
do research in depth so you can be more confident in investing.
indeed Bitcoin is the best coin but Altcoin is also good and he can be profitable besides that he is easy to get because the price is relatively low, but you have to be careful because Altcoin has a big risk.