Your sister is wrong for fundamental reasons.

Read Masters of Nothing: How the Crash Will Happen Again Unless We Understand Human Nature. The culture of greed depends on the active support of enablers and the effective silencing or marginalisation of all dissenting voices. In time, these organisations all come tumbling down creating chaos and disaster. Be it banks, companies or on the meta-level society because trust is the only thing holding us together.

So short-term greed fueld profit traded in for long-term, fundamental and irreparable loss in the quality of life. That is what your sister is actively enabling*.

My advice is don't be part of this, they are not worth your life's energy. Instead, seek out environments that harbour and nurture trust. If you know what you are looking for, you'll be surprised how many already exist. A good starting point is 100% (or majority) employee-owned companies. To understand what conditions booster trust you might enjoy > https://ncase.me/trust/

*https://www.openculture.com/2016/03/edmund-burkeon-in-action.html