In Sweden 'kids' in the 3rd grade of high school are old enough to vote, so they can certainly make changes - even without activism.
This attitude that "I am not in a position to make changes" is wrong. We can all make changes - if we choose to. If we fail to halt global warming it will because there are too many people in this world who expect someone else to do it.
If you recall grassroots gradual measures are not enough. I was told that many times. I don't believe that and still do my personal measures no matter how futile I was told it is.
The true Greta fans said we need immediate top level government drastic changes.
Like an immediate end to all use of petroleum products. Yeah, realistic stuff like that that.