You can always regret it or do something else. You could buy something more, and you still can.
Of course, it's too risky because 1 BTC costs about $16,000 now.
But there are plenty of other cryptocurrencies which can grow the same way the next year.
I am, personally, investing in DeepOnion. It's a pretty new coin and still quite cheap one.
But the developer team is working hard to make it the best coin. To begin with - it works via the TOR network and it's truly anonymous (not like BTC).
You can read about DeepOnion or join their community: https://deeponion.org/community/