I put together my own IoT infrastructure in our apartment. I did everything by hand: I wrote the embedded code, I wrote the server code, I pieced together the hub with a router and RasPi I had lying around. I spliced cheap WiFi relays into our IKEA lamps— and just to keep things simple, I also removed the original hardware switches.
The upshot is we have this nice web-accessible home automation system for a total parts outlay of probably under $100. It works really well! (As long as the Let’s Encrypt cron job is set up properly...) And most importantly, I know that I own it.
The thing about that is... I own it. I’m the only one in the world who understands how it works. I’m the only one who can fix it if it breaks. But I don’t live alone. If I pack up and leave, my partners aren’t going to be able to turn the lights on without going out to buy brand new lights.
And wow, that’s a huge amount of trust to put in me! Of course my partners do trust me that much, but it’s striking that I didn’t take that into consideration at all when I started the project.