Yes but not on purpose. I once sold bitcoin to a craigslist user at 10% over the spot price. They paid me via paypal, and it turns out they used a stolen account, so the payment was reverted a few days later. However, I had already withdrawn the money and bought more bitcoin with it, so my paypal balance simply went negative. That meant I had taken money out of paypal which I now owed them back, which is the same thing as a loan -- except I got it accidentally and had already used the money to buy bitcoin. There was no interest on this "loan" either. After not depositing any money into paypal for a long time, they handed my account to a collections firm. About a year later I finally paid them back, but only after bitcoin's price rise more than covered the principle of the "loan." So I made out like a bandit. But the "loan" was not on purpose -- it was a result of someone trying to steal from me.
I did well in the bull market, but didn't get out in time during the bear.
If you can get a low risk fiat loan over a long period of time it might be ok. I couldn't & ended up using 1 year loans on hodlhodl & ledn with high interest rates.
So be extra careful. I'm happy just DCAing into BTC. Don't have to worry or think too much. Just put your savings in until you have enough purchasing power to retire or semi retire.
You can buy bitcoin on credit cards and still come out ahead if you're willing to destroy your credit and are not trivial to service.
The amount debt collection companies ask for, is more of a reduction in amount from peak bull to bottom of the bear.
Now, that's just running the numbers. Getting on zero fiat is likely the optimal path for most people, unless they are young. Young people without a lot of money should be buying as much bitcoin as possible and defaulting on their debt.
Indirectly or for not selling bitcoins if cash flow is positive. I should learn this better. One my friend not a Bitcoin maxi at all but I'd say fiat maxi, he does very well. Better than me. He has financial education and extensively uses fiat system for his benefit.