Greta may or may not have known of the financial implications when she started out, but her parents probably did. She may be pocketing $100K, $150K a year as CEO of her ORG. A mighty tidy sum for her retirement. Her dad may be profiting as well. She may also be benefiting from perks paid for by the org. Her parent's probably knew that she would not have a normal like since she has been diagnosed with Asperger syndrome, obsessive–compulsive disorder (OCD), and selective mutism before her crusades.
Greta Thunberg uses the tools that politicians use. To speak out against climate change is to preach to the converted or to be for a matter that has no answer at this time as we do not even know if mankind can even reverse climate change. She spoke out against Andrew Tate, very few would side with Andrew. She just wanted to draw a crowd for her own personal gain. I would not be surprised if she has a team writing her script and she is just a figure head. They are careful not to attract powerful enemies like the Arabs and Russians. Why has she not criticized billionaires like flying in private jets.
Let me put it this way. If Greta Thunberg were to get on a commercial flight and brought several people with her her group would not even increase the fuel consumption anywhere near 1/10 of 1%. What is your estimate?