Sometimes it's not just about longevity, it's about how the product feels. This is especially true when it comes to our online content and- as adults- we have less time as we have children. Meaning quality is more important than quantity.
I think mechanical keyboards are a good example here, but maybe not in the way you were expecting. You may note that most PC sales are laptops these days, and nearly all of them eschew mechanical keyboards in favor of other priorities. And also, most desktops still ship with membrane keyboards, and only a tiny fraction of users replace them with a mechanical keyboard -- as you say, "techies". It's a niche preference that "most people" (from the title) do not find value in.
It's not a binary choice.
Price is a non-linear factor here: "quality" may be prohibitively expensive as a single purchase, even if it is less expensive over X years than re-buying a cheaper item every year.
In the US, shopping trends are clear that many people (perhaps most) value quantity very highly, to the point that they will sacrifice "quality" which is loosely defined and more subjective. IME this also ties into Americans being very price conscious.
They definitely are "better", as in they're a pure luxury good that serves no purpose outside of being a higher quality product.
There's really no value that a mechanical keyboard that can give you that a standard chiclet keyboard doesn't give you, yet, it's a quite large industry with many disparate manufacturers and standards and so-forth.
There absolutely is, if you spend all day typing. Chiclet keyboards give poor tactile feedback that for many, leads to more typing mistakes. There is also value in the "pleasantness" of the experience - it's hard to quantify, but if it feels better to use something then you are certainly getting value from it (for another example, a cheap and uncomfortable vs expensive and comfortable chair).
I don't know what percentage of mechanical keyboard users this is, since there are certainly many that view it as a hobby or collector's interest, but I am one of the other side that use them exclusively because they make typing easier and more comfortable.