Thoughts? What would you do?
The flaw with that thinking is if a coin does the 2x thing, it will drop at least short-term. It's inevitable. Then you'd be better off simply selling and buying back in, and either going with more coins or some profit.
Also no guarantee that if BTC hits 15K, that said alt will retain its value at year's end. BTC doubles and your coins sinks like a stone at the end of the year, it's less profit.
The biggest issue I have when my coins do the big pump thing is the fact that many are flash pumps -- blink and you miss it. So it means guessing at where to set sell orders ahead of time, and odds are they won't be right.
I guess that's the reason you sell some of your coins when their price jumps or convert them to BTC. If you hold alts you can lose in value even if the alts jump in prices. Weird but true.