That view is false. People act for a variety of reasons, some selfish and some humanitarian. The basic postulate of economics applies to both the altruist and egotist. The choices of both will be influenced by changes in personal costs and benefits. For example, both the altruist and the egotist will be more likely to attempt the rescue of a small child in a three-foot swimming pool than in the rapid currents approaching Niagara Falls.
Incentives influence the choices of both.
There is no such thing as a free lunch. Scarcity constrains us. The reality of life on our planet is that productive resources are limited, while human desires for goods and services are virtually unlimited. Since we cannot have as much of everything as we would like, we are forced to choose among alternatives. When resources are used to produce, for example, a shopping center, that action diverts resources away from the production of other goods that are also desired.