I don't know why I find this story so weird. In as much as I am very much sure that owning 1btc is a good business and you will never regret it, but the huddles that you passed through to own the 1btc doesn't really worth it.
Maybe I am just being me here. If you have a nice source of income, an initial investment of $6k is not bad, I wonder why you acted as if there was gun on your head.
I would not be able to live a debt life for two years in order to make massive profits, especially when it involves investing in a volitile assets. Let's assume your story is real, then assume that btc goes to $10k, what will be your state of health?
I don't know if what the OP did was too bold or a bad move, because owing someone else to invest in something as volatile as bitcoin is definitely not the right move, investing in bitcoin is a good move if we have the funds cold or personal, but by borrowing other people money we will only increase fear when the market goes down like this especially when the debt is due, I agree with you, it's better to invest $6K with the money we have and at least we can sleep no matter what the conditions happend, rather than of having 1 BTC, but we are overwhelmed by fear and trouble due to debt.
To borrow money from a relative is somehow better, because the deal can be re-negotiated friendly if something goes wrong, but the worst part of this story is to be in debt with the bank. They are going to charge 10% annually for the loan! And there aren't any guarantees bitcoin will double its price soon, but he will have to repay the loan without any excuses, with or without profit from bitcoin fluctuations.
In my opinion it's one of the biggest mistakes someone can commit in financial world. Banks' loans aren't an option because they are abusive, treacherous in case you don't repay them on time and give no real benefits to the borrower after all. It's better to not have money to invest or invest low amounts of money than contracting a debt with a bank.