No way there's a safe long term investment, it always comes with a risk no matter how careful you are. However given how crazy the market is, even a useless token is a good investment. Long term holding will surely be fruitful especially now that the cryptocurrency is now being recognize around the world.
every action has a risk not all coins are not safe to invest in the long term for example ethereum everyone who holds ethereum coins in the long term they can profit a lot. My advice, if you want to hold coins in the long term choose the top 10 there is a chance that you will get a profit.