I think it's still safe to invest in cryptocurrency in the form of bitcoin or ethereum because so far I see only these two coins are suitable for long-term and safer investments because the price will always go up. while for other altcoins I'm not too interested.
yes, both are performing as Gold, sometimes goes down even for couple of months but if you don't sell you will always have profit.
but some other coins are stable as well, at least not going to hide under top 50 over time like XRP, USDT, BCH, LTC and EOS