I used to run/part own a national and then international...

I used to run/part own a national and then international consulting firm. We got too big for it to be fun anymore and it became all board room politics. I can't imagine going back now. Now I answer only to myself. People think that "heh it must be fun to be the boss" - but it is and it isn't. The secret of being the monarch is that you are enslaved to those you "rule", because the real secret is that you only rule while your "subjects" are prepared to let you rule, and part of that deal is that you become responsible for every decision they don't want to make or be truly responsible for.

The problem with being a solo consultant is that you need to sell the next piece of work, and while you are marketing you aren't earning, so naturally one starts to add staff so one can sell while the others earn, and vice versa, and the more staff you add the more time you have to give over to managing them and the brand. The other problem is that technology and markets never stay the same for more than maybe 5 years so eventually you have to reskill or refocus your market segmentation. The transition when it first arises can be hell.

I'd say the sweet spot was a firm of 10 (one admin), then 30 (2 admin) that was when it was the most fun. By the time you climb to a few hundred staff it becomes a money making machine but it is more a bureaucracy than a fun, thriving, and exciting "gonna change the world" experience and it is non-stop politics and travel. At least as a management consulting firm. It did make my current life possible though.