Well fuck me, we might as well sell everything now then?
If you don't think that an ETF or similar big boosting event is likely in the next ~year, then that might end up paying off, but personally I wouldn't sell large amounts now. First of all, it'll probably at least touch $6k in the near future. Second, you don't know when an ETF will be approved or the next 2008-style financial crisis will happen, both of which could truly put BTC through the roof. (Insider trading will probably put BTC to $10k+ some time before an ETF is actually approved.) Third, while cryptocurrency will probably not take over the world anytime soon, it's a very real and growing niche which isn't ever going away, and I see no serious competitors to BTC for king of the cryptocurrency space.
It all depends on your risk tolerance and time horizon, though. If there's any BTC price that would ruin you, then it might be a good idea to sell some.