This is kind of a shitty time to buy a PC. DDR4 prices are at twice what they were a year ago: https://pcpartpicker.com/trends/price/memory/
And what Cocco said about gpu's. If you can, wait 2-3 months because that's when nvidia will push their new toys and at least gpu prices should fall again.
But with that said, you can still get a really good system for $800. What your friend said about AMD kinda makes sense. Hardware doesn't "break in" but ryzen might still have some early adopter issues and might require you to flash the bios after an overclock fails or for compatibility down the line, and that could look really scary to some people, but really isn't.

I would definitely not get a 1050 in a gaming system. You can get a used 980TI for less and it will outperform the 1050 by a good margin. If you insist on buying new, you can still get something better than a 1050 in a $800 system. PSU used prices are always in the dumpster, so I'd always recommend something like a Seasonic 450w for $20 than getting whatever noname brand new for 3x the price.
It also has the added benefit of maybe getting a really good combo deal for MB/Ram/CPU from people who are oblivious to the DDR price hike. For example I just saw a local ad from someone selling a 4790k with MB and 32gig for little more than what the current street price of the memory alone is. Hardware with non-moving parts doesn't go bad over time. Thermal compound on CPU's and GPU's is what you should change, but anyone can do that.

At $800 I'd definitely buy used. If you don't need super high framerates you could get away with a 4690k and a 1080. If you don't have a 144hz display and you're not looking to get one, that's a reasonable combo. The only time you really want to spend a good chunk of your budget on the CPU is if you need to get high framerates out of ubisoft and activision games, or you do a lot of other work that requires a lot of cpu power.