A lady told me that she paid 130 euros a day in Amsterdam, and she shared that apartment with another lady. It was a nice location, though. But a luxury two-room apartment where both had a private room and had to share the kitchen and shower. So it was rented out for a total of 260 euros a day. Per day.
Those ladies have already earned back the rent after just one visit. So you really don't need to feel sorry for them. It wasn't a bad location, but it was nice and spacious. But these are the prices, you see. Just calculate how much this brings in per month. If you assume a 24-day rental for 250 euros, you're already looking at 6,000 per month that an apartment like that generates.
The mortgage repayment won't be more than 2,000 euros, so such an apartment yields 4,000 euros per month. That deducts all costs.
There are probably also locations where people pay a bit more. Because it can be even more luxurious.