Egg boiler. On the surface it's just the most gadgety pointless product invented but I literally wore it out because suddenly I could have hard boiled eggs and no risk of setting my apartment on fire because I forgot about the eggs. After I move, it's the first thing I'm getting for my kitchen because low-risk hard boiled eggs are totally worth it.
There's a lot of seemingly 'useless' kitchen gadgets like this: full size food processor, waffle maker, breadmaker, even my ridic large instapot. I don't use them every day or even every week and no, I don't need them for daily life. Yes I can mince fifty thousand vegetables for this really complicated soup by hand or make bread from scratch or do whatever you do to make a pot roast without them--but I won't do those things. I know me pretty well now; if I want to make that soup, make some fresh bread, or do that thirty-step fancy pot roast, I need those tools or I'll default to frozen pizza and maybe have fresh Italian bread if I went to Central Market recently and remembered to grab it from the bakery.
I started vaping seven years ago as a way to quit smoking; I smoked my last cigarette literally outside the vape store before walking in and asking what to I buy to pull this off as nothing worked. The transition was seamless; not only did I never even crave a cigarette again, I very quickly learned to loathe the smell of cigarettes once my full range of smell came back. There's not even a temptation to start up again.
It also helps that I choose vapes that smell amazing.
I am still vaping, yes, but I'm stepping down my nicotine pretty much every two years. I started at 24 and am now at 15 (I was stuck at 18 for a while). Those transitions I can definitely feel, but I can start with adjusting my mod's wattage, air flow, use different coils for a bit, and ease into it so once I step down, there's no chance I step back up, and then reward myself sometimes with a new fancy mod with a touchscreen with more leds or a cooler tank or something. All that and I am spending an order of magnitude less than I ever did on cigarettes and I have the math to prove it.
It's certainly not ideal and yeah, it's slow and basically only progressively reducing harm, but it's a process that for me is guaranteed to work with no backtracking and progress is assured.