As long as I don't weigh my ideal weight and aren't planning on becoming a machine myself, I have zero interest in spending anything in optimizations which will make my bike a better one. I don't care if it could go faster or be more lightweight, spending 600€ for the bike was enough. The cheapest 30€ Schwalbe tires are good enough; I didn't even have a single flat tire this summer after I learned to avoid driving over blackberry branches.
And I really enjoy it. During this summer, with the extreme heat, where I loved the 28°C in the shade of the woods I was thinking about how much I'm going to hate this fall, and now that it's here, I love breathing that cold, fresh air and smelling the humid forest. The only thing I hate is when there's frozen snow on pavement in the winter.
The only thing I spend money on for biking is quality clothing appropriate for the seasons and accessories like good smartphone holders or bags.