There's a demand for them. SUV are quite popular for families who don't want to "drive minivans" but they still want a large vehicle to fit in everyone. Others buy it because of the perceived safety, larger vehicle so they feel more "protected".

Trucks are just what you drive in rural areas. And there are a lot of small towns and rural areas. Companies noticed that people are shelling out $40k for them, so they started selling them for $50k. $50k and they are being bought still? Ok, time to charge $60k, and so on.

Think about this - the same amount of tech, of engineering, of “stuff” like window regulators, speakers, steering wheel, etc goes into a subcompact 4 door as does a 4 door SUV, minus cheap stuff like body panels interior carpet.

They have them because people are wiling to pay for them. People are willing to pay because they think they are worth it. I would guess that the fact they are bigger make people think they cost a lot more to build, when they do not.

Because that’s where manufacturers need to make money. These things typically have fuel economy numbers at or below CAFE standards, so they’re banking on these and selling more efficient vehicles closer to cost.

At least some part of it, and perhaps a majority of it is due to chicken tax. Trucks in the US enjoy a level of protectionism few other industrial products do. US manufacturers, as a result, can increase their margins without losing market share to foreign competition.

https://en.wikipedia.org/wiki/Chicken_tax

Because they can?

As utility vehicles, they also tend to have really good resale value, so they might not be quite the poor 'investment' you imagine.

Because the resale is good, margins can creep up. There's nothing holding them down.