Borrowing money at $19K, is not smart. I also know that getting loans at $10K and selling right now would have been an amazing idea. Personally, I was trying to get loans in summer for a quick 2x flip, so I don't believe it's always a bad idea.
No, it definitely isn't a bad idea but the things is that you still take on a gamble as you don't know what the market situation a week or a month later might look like. Looking back now obviously you feel you could have done it when BTC was 10K but that's because you already got the knowledge of today's market.
Having said that it definitely is a strategy worth investing more time into if that suits your schedule, and of course it depends on you and if you think this might work out well.