The only investment I've found that's actually worth it is a home entertainment network like plex. Having all my family videos available in every room and every device connected to my Wi-Fi with a few clicks or a link and a shared user account has been worth the dozens of hours I've spent building my library, rebuilding my home server, upgrading components, managing updates, and debugging edge cases. Would I like lights to turn on and off when I enter and exit rooms? Yeah, but smart switches don't cover all of my use cases naturally and without manual overrides and the convenience isn't worth the thousands of dollars to retrofit my house for an immature technology.