I know this isn't popular opinion, but now that bitcoin has reached an undeniable ATH, I'd strongly advise you to take some profits off the table.
I've invested far too much of my money into bitcoin since mid-2013 and I've never been more confident than now. Yet precisely because of this optimism, and because of the price growth we've seen in recent months, I sold a small portion of my holdings. ~5%. And I will continue take small profits if the price continues to soar.
It's always good to take money off the table if you're in the black. The best thing in the world is to be playing with the house's money
It increases endurance for the long-term. We're all in it, I hope, for 2020, 2030, and beyond, and taking profits off the table when you're doing well, like taking breaks during a marathon, will help you endure the next boom-and-bust cycle...and the next...and the next...
I'm not so rich that my bitcoin investment is play money. It helps psychologically to feel like I have actually made money, not just on spreadsheets, and I can use this money to diversify into other investments like index funds. Yes, index funds might not be as exciting as crypto, but diversification is the cornerstone of solid long-term investing
In the long-run, I don't know if bitcoin will maintain its #1 position. And over time I've slowly increased my altcoin holdings and am roughly trying to "track" the cryptocurrency market by market cap (with some exceptions). So part of it is rebalancing as well
Just as an example of how weak I am in my resolve: I had made a self-promise to sell 20% of my bitcoin holdings when it reached the ATH, and now the day's here, and I could only bear to sell a quarter of that...
Just some thoughts I had recently and wanted to share.