Profit is just margin. The difference between what you pay for something and what you sell it for. If I travel to a far off land to buy spices, bring them back and sell them to you for a price that is worth more to you than the money you trade, both of us win. The margin is what you were willing to pay for someone to go get those spices for you.

If my neighbor can find a way to make the trip more efficient, he can give you a better price.

We compete and prices fall to the marginal cost of production. The world gets more efficient and thus we are all better off. Everyone's money is a little more useful and so we all get richer.

Rent seeking is I have a thing you need, or I can get the government to force you somehow, so I use my leverage over you to extract the maximum I can take from you. Often that will be more than you have, by a bond ("loan") so I take your freedom and then I can sell my claim on you future work and set up enforcement, regulation, etc.

One is a freely negotiated exchange of value, the other one is extortion.

We live in a world where these waters have been intentionally muddied. They have pretended that rent-seeking is fair play, called it "profit". Some people have reacted, understandably, by saying "well profit is evil then." But it's not. Profit is good. Usury is evil. There is a reason why that word is old and strange to us.