I used to have a custom built computer to be the firewall/router on my network. $400, ran OpenBSD. Full enterprise level software stack all open source. Dedicated access point with PoE under $100. Separate managed switch, $250. Under $1k for a full network, custom built, more featured, and far more powerful than any of the routers you can buy which include all of that, if they can. Good times. The router machine ended up breaking down when I got metal shavings in it, so now I'm using a shitbox router with my access point connected to it. The router's Wifi radios are disabled so it can concentrate on routing.

Point of diminishing returns.

Then you get all those people who think mesh routers are great because they have "poor" signal. No, moron, it's because there's 100 APs on the air in your area and the bands are saturated and now you just added a half-dozen more problems to it.