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.If that market is greedy, it's never a good idea to risk more than you can afford to lose. But if you "know what you're doing" and quite sure about things, then getting loans and throwing them into encrypted currency isn't always the worst idea. It's how some have made the most money to be honest.
I also recently invested more than I could afford to lose (going from 95% in to 98.5% when price was around $10-11K). Best decision I ever made! This was also on the basis of selling the 3.5% when price broke $18K, as it's actually money I need

You can actually make even more if you do sell of that 98% gain for yours and tend to get the profit and paid up that loan with the earnings you had then you do reinvest when bitcoin plunged back to 18 or 17k possibly
before it would make some another run.
Better to secure those profits and repay loans so that there wont be anything to boggle up your mind.In case the market had flipped down to 10k again then you had at least secure your profit
and if not then you would go back to square one and paying up the loans with interest came out from your pocket.
Borrowing isnt bad but at least you do aware or know the risk involved.