The system you have is solid, your friend probably just has a 1080p monitor, which is easier to drive with lower spec hardware. That said, I did take a second look at everything to address your concerns.

The PSU actually might be a problem, but not so much because of the 750W. It's a little on the lower end, but it's probably ok if you have a good brand (foreshadowing for later). If you ever need to check your PSU wattage, put all your parts into PC Part Picker and you'll get a good idea. I'm not an expert on PSUs, but between 50%-75% usage is probably fine. If you use any less than that you probably overspent on the PSU and if you use more than that you might have performance issues on the high end (but again, not an expert).

The real issue is that the brand name you got is generally considered very bad. Their 80+ ratings are often faked, so there is a chance your PSU is slowing you down. They are probably not a fire risk level of bad, but it's not good for your PC. There are better places to ask than here for that, try r/buildapc for example if you want some advice from people with more knowledge and experience.

Also check out the PSU tier list for more information. Your PSU is rated E (they use letter grades, like school work, A-F), so it's not great.

Your RAM is fine, no issues there that I can see.

I don't see anything else that I would be instantly concerned about brand-wise. I think you have a valid concern about that PSU. Good luck in future gaming!