Some businesses share their profits equally amongst their owners - they consider that, although different partners might bring different skills and experience with them, they're all contributing in their own way and everyone's happy to share the rewards equally. It's a good way of doing things.
Some businesses share their profits on the basis of how "well" each owner has done. They consider that the partners ought to be rewarded/incentivised for their own efforts, skills and experience. It's also a good way of doing things.
The problem you get is when some partners think they're in the first type of arrangement, and some think they're in the second type. So getting that discussed - and maybe documented in a partnership or shareholder agreement - at the outset of a new business is a very sensible thing to do.
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