I want to build some credit in case I ever need a loan for something. I have never had any debt except for my credit card that I now have for about a year. But I only used it for a single purchase in Germany to make sure it works and then when I traveled outside the Euro zone for a short period of time, so hardly any activity there. I don't feel comfortable using it for regular purchases for a variety of reasons.
My idea for building credit is to take out a personal loan such that the amount I have to pay each month is about how much I'd put into stocks or index funds anyway. I can then put money into the market for a bit longer and build credit. I also get to save the fees for buying stocks or index funds often / buying them via a monthly plan. Saving on those fees might very well be worth the interest payment. There is no way I will end up in trouble keeping the payments up because I have more money than I'd take out in an old bank account that I can cash out on at any time but don't do so because it's got pretty high premium that I get each year.
There is a "deals" (special offers) website I frequent that sometimes contains offers of personal loans that pay bonuses that can be higher than the interest you have to pay if you get the lowest-possible interest rate. Obviously I won't get that but I'd see whether what I have to pay extra is worth it to me.
However, other people in the comment section had the same idea (well, they talked about bank accounts, so they want to take less risk) and there were others commenting that that's a bad idea because (they claim that) a consumption loan actually reduces your credit score even after you paid it off.
I live in Germany and am a German citizen, in case that's important.