the "rulers" are born into families that are well off but still need to work - in other words, comfortable/professional middle class.

Bill Gates is basically a lottery winner with the savvy to use his winnings cleverly. There are always a few of those, people who got lucky and used their luck. Always have been, even in feudal times.

Recognising socio-economic class as crucial in how society operates doesn't mean that rich and/or well connected people never work any more than it means that poor and/or powerless people aren't ever indolent. But it does mean that, overall, those aren't the things that are in the driving seat.