People like to sit up higher so that they can see over the other people who like to sit up higher, recursively. People like to have a heavy vehicle so that the

People like to sit up higher so that they can see over the other people who like to sit up higher, recursively. People like to have a heavy vehicle so that they feel less at risk in a crash with other people who like to have heavy vehicles for the same reason, recursively. The base cases are more mysterious.