There are a couple things I've noticed that makes me play the Deck more. First, being able to play on the couch while others are watching the TV helps a lot, although this is also true of the Switch. Also, emulation is so easy on the Deck, I find myself picking smaller sessions of older games (mostly SNES and GBA).
I have a couple of other hobbies that consume my free time. Since getting the Deck, I've allocated more time to playing games on the Deck and a bit less from the other hobbies.
I'm not sure what would make me buy the next generation of other consoles. It'd need to be something fairly compelling, but I don't see a gap in my personal gaming that's going unfulfilled. I think I could slim down to just the Deck or its successor for the next gen (and maybe the gaming PC, depending on performance).
One significant attribute that I suspect separates me from many other gamers is that I have nearly zero interest in games that are heavily oriented towards online multiplayer, like most FPS. This keeps social network effects from pulling me into any one of the consoles. Some of these have games cross play, but that wasn't the majority a few years ago.
Also, having access to Steam’s frequent discounts - a lot more frequent and generous than Nintendo’s - is really nice. EDIT: forgot to mention - there’s also the fact that you can get other game stores to work, you can even install Windows if you really want to.
I also trust PCs more than Nintendo when it comes to future portability and compatibility: I know for sure I’ll be able to play all my PC games in the next iteration of the Deck, and other PCs of course, and even if Valve folds I’ll be able to use the Deck for whatever I want. You can’t say that at all for the Switch - eventually Nintendo will pull support and bring down the store like they did for the 3DS, and they even patched it one last time to make jailbreaking harder! For a DEAD console!
EDIT: A point in favor of the Switch though: games come in cartridges so if you don’t want to trust online stores in the long term then that’s something to consider.
All this being said, I found the Deck to be a little too underpowered for my use case - it struggles with some of the games I like to play. I ended buying a Razer Blade 14 with a 4070 and an AMD chipset. Not as portable, but still very portable, plenty performant and with great battery life.
Right when it came out, I was looking for a laptop I could use on the train to game and do some compute with without breaking the bank and it's one of the best price/performance ratios out there.
Since the steam deck can also play all my switch games plus a lot more, this is what I tend to use and carry around for my personal use. The only problem was installing and letting them know that they can play roblox and minecraft on it so now they constantly want to use it instead of their switch.