A few points that I think are valid.

Some of us have zero desire to "build our own". That's a hobby I'm just not interested in. I found the rifle I like and I bought it. It has a couple of glaring deficiencies but they can be fixed cheaply. Mainly it needs a better handguard - one with a heat shield. I bought one for $30. Works fine.

If you're looking to shoot 500 yards you should not be buying an AR IMO. You can't match the accuracy of a bolt action rifle without spending far more money. Semi-auto isn't a real important part of a long range rifle. I spent $900 for a bolt action rifle (bought it slightly used) and it will shoot 5" groups at 500 yards all day as long as the wind isn't extreme and that's with 75 gr. .223 rounds. Off the shelf rounds at that.

You can probably build a rifle equal or better in quality to the Sport. But you won't get a lifetime warranty and the support of a long established company. For someone new to the world of AR's to jump in and build their own they are taking a big risk on getting it right the first time. You could end up spending money to correct mistakes and then your good deal goes out the window. I went down that road trying to get an AK built from a kit. The person who talked me into that saying he could build it in an hour was still shooting my ammo trying to make it work right 6 months later when I sold what I had for what I had in it. I was getting eaten alive by a good "build your own" deal.

Again my Sport shoots pretty accurate for what it is out to 150 yards or so. I haven't had a chance to shoot it farther than that. It goes bang every time I pull the trigger and AFAIK it has no real deal killing problems. I have seen lots of entry level AR's that did have deal killing problems. Lots of them.

And it's been said before but the initial buy in price for any gun is a small fraction of what it takes to operate that gun unless you just want a gun cabinet collector's item. I bought a $500 .22 a few years back. The first year I spent $3500 on ammo for that rifle. The first year. I've spent way more than that since then. If you intend to actually do a lot of shooting expect the price of the gun to be less than 10% of your operating cost over the first few years and even less over time. Heck I bought a $100 .22 25 years ago and put 150,000 rounds through it. I bought a $90 SKS and put many thousands of rounds through it. Even when the ammo was dirt cheap it still ended up being way more than the rifle.

To me the bottom line was the warranty. But the Sport also had everything I wanted and nothing I didn't want. I wanted an AR that worked well for not a lot of money and had a good company behind it. It wasn't a close decision at all for me. Since then other good companies have gotten into the entry level AR business and likely as not they are similar in being good deals. But there's still nothing really that beats a Sport that I've seen for a first time AR buyer on a budget. I could have spent a lot more on an AR if I wanted. I see diminishing returns on that extra money spent to be honest. You will pay a lot more for a rifle that isn't a lot better.