Losing 50k on a first condo in which I dislike living

Hello!
I'm quite depressed about this and would love to hear your opinion.

I bought a condo at the peak of the market on Dec. 21 for 310k, I felt like it was overpriced but it was my first acquisition and I trusted the realtor who said it was a gem. It's an undivided condo, so I can't rent it, and it makes it harder to find a buyer later. I was not feeling well at that time, and I wanted to buy it for my sister. If ever something happened, she would have it. So I went along and made an offer, which of course they accepted.

One month later, when the previous residents moved out, I stayed there for a week, and it was just awful. The condo is on the top floor of a building, and we can hear the ventilation inside the whole apartment. I went to the roof and I am no expert, but I am pretty sure it was caused by the old vents that are fixated right above the roof. It did make the same sound when I was in front of it.

I am super sensitive when it comes to sounds.  I don't want to be a picky person because I am not. I could live in an extremely small basement, as long as it's clean and quiet, I am happy. So imagine my reaction after realizing this. I asked my neighbor and she said it's always been like this. Sadly, the management said they would fix it, but it's been 5 years...

1 year later, somehow, I had never been so unhappy. I realized that I could have left my sister with so much more money instead of buying this. The prices are falling and I may lose around 50 to 60k if I sell this year, and I am willing to reduce the price because of the noise from the roof. I want the buyer to be conscientious about this so he doesn't have the same surprise.

I feel like at this point there is no reason to sell. I've already lost so much that I may as well keep it and try to convince the management to fix the roof. There are 40 units and only 5 on the top floor, so I understand that they don't consider this urgent.

But at the same time, it's giving me so many regrets, and I feel dumb to not have been more cautious when sending the offer (the realtor was so eager, and the whole deal was done in 3 days including the initial visit, but again, I know It's entirely my fault). The idea of losing that big chunk of money will keep hurting, but at least my mind will be at ease.

I am 32 and make about 40k if that helps put things in perspective. Sorry for the vent, it helped to write about it as I don't talk about my personal stuff IRL.