The issue here is definition of useful/useless. If you manage to market regular rocks as magical and convince people to pay a lot of money for them, a capitalist will gladly pay for everything from digging to shipping of those rocks.

From a common sense perspective that activity is useless because it's purely wasting resources with no useful effect. From a capitalist perspective the activity is not useless as it brings profit.

And yet if you spend any time in any large corporation, you'll find countless examples of these, including in the tech industry. Don't you have any friend working for Google/Meta/${big tech co}?

Bullshit jobs can and definitely exist with capitalism: any successful and large business is filled with them.