> How so? I know a guy who has literally millions of dollars tied up in shit that moves dirt and rocks and another mil tied up in some gravel pits

Having literally millions of dollars in productive assets is rich by any reasonable standard.

> The free cash he has, the house he lives in, the lifestyle he can afford is on par with "normal" white collar professionals

And he has decades of support at that level of wealth in and realizable from the assets. Choosing to use it to generate a a “normal white collar professional” (i.e., reasonably well off to start with) income doesn't change that it is an enormous store of value that he owns.