[giraffe_lady]

Part of it is also just the field maturing. For a solid generation or two car tinkering was accessible and widespread. American culture still has a lot of influence from this but as cars matured and became more powerful and reliable, the need to do it and the threshold to get anything out of it changed. I think the latest new "niche" in that domain is the import tuning scene, decades old at this point.

Some tinkerers do it because they just enjoy the tinkering but for most I think it's a combination of enjoying it some while also getting some tangible benefits out of it. When any device you could easily DIY is available off the shelf, the cost-benefit changes. You have hard DIY left, but not easy tinkering for moderate gains.