There's 3 things that really stand out for me that I would say made a massive difference to my life:

1. Cordless screw driver. Bought the day after building a flat pack bed with a crappy screw.driver that just shredded my hand. Thought it was frivolous at the time, but I've used it so much since. It's light, small enough to fit in my pocket and good for 90% of DIY tasks.

2. Tassimo coffee machine. Bought it 9 years ago, use it every day. Nice quick easy coffee. What's not to like.

3. My first DSLR camera. It was a Nikon D50 back in 2005/6 and it sparked my interest in photography to this day. It gave me a hobby I can take lots of places and do it alone or with others. I never loved the D50 camera itself, but I did get some really nice shots with it