Really, a sensible and thought provoking question, I also had a same question many years and it got stuck into my mind and I kept thinking about when ever I was free.
The crisp answer is “NO”. No one is getting poor, if you are making money. I will explain you a third component which is Nature or Universe which is balancing everything.
Example 1: Trees are coming from nowhere: Suppose you plant 100 trees on a farming land for selling the wood in future. Trees after 10 years are ready to be sold. You sold them, got money generated simply from the air. You did not do any thing except planting them and giving water in few initial months. (so in this case money is not coming from people, it is coming from Nature and your hard work)
Now the person who has bought wood from you will recycle it , make furniture, doors, windows etc and or may sell it further.
Think about Abundance: We are thinking in terms of scarcity most of the time while we should think of abundance. If one truck of Uranium (or some other Mineral/Metal) bought from moon would be sufficient to fulfill the requirements of US for one full year, But we are fighting for limited resources.
Example 2: Consulting services offered by you are being generated from your mind and they are benefiting people so they are paying and your knowledge is adding value in their carrier. So this money is coming coz of mutually beneficial relationship.
Under this Example let us take different cases:
Case 1: You tried to help and the person got benefited. In other words Doctor operated the patient, did the surgery and operation was a success. Both Party are beneficiary. Doctor gets fees and Patient life is saved. Will you not feel good and accept the fees as a doctor?
Case 2: As always you tried to help but the client or patient did not benefited. In other words doctor tried to save the operation but the patient died. Now in this case doctor is a beneficiary, while patient has lost life as well as money. However does this means Doctor should not receive the fees?
Example 3: You sold goods/ service to other people and they further sold it at profit and the chain continued. So no one became poor. By the way the goods you sold were perishable and they got damaged at one person’s ware house after changing hands from two suppliers. Whose Fault? This person surely will get poorer. Should you regret?
Example 4: You sold a Gun to a Eskimo, he will gain from it by hunting, you gave a nice thing in nice hands, but if you sold a nice painting to Eskimo what will he do from it? This will surely make him poor.
It requires a lot of introspection on what we are doing and for what purpose we are doing it and does it makes us satisfied or it increases worry inside of us after we do it. The real key lies in what we feel inside after we do that action.