The Position
Take From Both Sides.
You stand between two people who both benefit from you. Both can pay.
The amateur middleman charges one side and feels lucky to get it. The professional understands that both sides are getting something they couldn't get alone - the buyer gets the solution, the supplier gets the work - and so both sides can fairly contribute to your cut. The supplier pays for the deal flow. The buyer pays for the solution. You collect twice for standing in one spot.
Done greedily this blows up. Done well, with each side genuinely better off than they'd be without you, it's the most natural thing in the world. A recruiter is paid by the employer and adds value to the candidate. A marketplace charges the seller and serves the buyer. Find the structure where both sides win, and let both sides fund the doorway.
Both sides win because of you, so both sides can pay. Collect from each.
This is one of 48 laws from MIDDLEMAN - The 48 Laws of the Money in the Middle. Read it in full to climb the whole building, floor by floor.