It all depends on the terms of the loan and what you are buying with it.
Banks can offer very good deals if you know what to look for.
Banks essentially service the rich and the savvy.
If you are one of those you can probably find a steal somewhere under good economic conditions.

Taking a look at the failures: why did 2008 housing crisis happen?
Because a bunch of noobs who should not have even qualified were being given variable interest rates that skyrocketed when the market turned sour... it was all right there in the paperwork but the poors trusted the greedy real estate agents that were shilling these contracts.

Taking a low interest loan can be akin to gambling with money that isn't yours, and within industries like real-estate these gambles are often considered extremely safe and viable even by skeptics such as myself.

It also depends on what time it is during the BTC 4-year cycle.
You're not going to want to sell at the bottom of a bear market, making collateralization ideal.
Of course right now could arguably be a fine time to do it being 30% from all time highs.
At that point it just depends on personal finances, portfolios, need, and risk appetite.