At the moment what you put in is what you get out of it. With three people, what happens if one person is sick or has an off-week.
Will you be a bit miffed that you are working your (wheel :
) nuts off whilst others are gaining the fruits of your labour?
What happens if the other two want to take the company in a different direction to you & you don't agree?
What happens if the other two want to buy themselves/the company two new vans that you can't afford. You object but you get over-ruled?
Don't say that'll never happen!!!
If any of these scenarios, or worse ones, make you uncomfortable then it's time to trust your gut instinct.
Hope this helps.