BTC and ETH both undoubtedly safe to invest at any time but why peoples investment on other new projects because they need early profit which is not happen in BTC or ETH. New project is always risk because i have seen 90% is scam at end of the day right now.
There are very many new projects that end up being scams and that's why investing in new projects is very risky,
indeed sometimes someone wants to take risks but it needs really mature consideration,
it is better to invest in Bitcoin or Ethereum which for long term investment is much safer.
I think it only becomes very risky if one randomly invests on them but for someone who knows what he is up to (does a proper research) then they can possibly avoid the scam coins. They will also know how to prioritize the old coins, so that they can still get something and possibly recover what they have lost from investing in new coins.
If our goal is to earn quick profits then that is still possible with the old coins most especially Bitcoin as it was a highly volatile asset. We can use it for trading other than short-term investing. If we still can't get enough then we can also engage in gambling (casino or sports betting) both can also offer quick profits as long as we are lucky of course.