No I would avoid it. It is always a gambling activity. This is just an useless risk.
First of all, even if we are ultra-optimistic in this forum you cannot know more about "the future".
If something goes wrong (and this is always possible) there is a loan to be paid back plus no investment available (imagine a big dip or whatever).
This is only an un-necessary risk... also because you can have extra expenses and liquidate your investment will become an huge failure.
Big investors are aware of people trying to get these jackpots and collapse of the prices are always possible.
Well saying gambling somehow reduces the status of Bitcoin as an asset. However, borrowing cash into DCA is a kind of uncomfortable approach. Better and easy when it is based on as much as u can afford....
A proper self analysis will reveal his friend to be gamble minded which for sure unhealthy so far as DCA is concerned.
DCA can't be embarked on by borrowing, u invest as much as you can provide not otherwise since after all it is a long term investment approach...