I regret ditching my position on Doge, but I flipped that into BTC so I dont feel too bad.
Sadly, I think we're long overdue for a 51% attack on a somewhat prominent coin. Doge (to me) seems like a potential hit as it's merge mined with LTC. Who knows. Either way, people who have held are seeing a pretty nice return.
ETH, I worry about those transaction fees, gas costs and the perpetually growing supply of tokens. I worry that the way tht blockchain is evolving, something comparable, faster and cheaper will start siphoning off market share from ETH. I equate holding ETH to holding IBM since the late 90's. It's not going away, it's not going to really crash and burn, but at some point youre going to hit that ATH moment and may miss out your opportunity to cash out. That being said, ETH is still about 8% of my crypto portfolio. It's one of the 4 coins/tokens I believe in, along with BTC, DCR & ELA.
With the exception of Filecoin, I've given up on trying to time jumping in and out of certain coins