It doesn't take a billion and that is good because what you said is not true there are not a billion people "who care and will do anything." Probably not a billion who care very much at all.
The total population of the G7 countries is less than a billion and at least half of those people don't care enough to take any action to fix the problem. The rest of the world barely matters. Those people either live in poverty, have bigger issues or are in authoritarian countries where protesters are punished severely.
We don't need a billion protesters, but we need at least a million. XR is just not big enough yet. The people are still not ready.
In a YouGov poll of 3,482 British adults conducted on 15 October 2019, 54% "strongly opposed" or "somewhat opposed" Extinction Rebellion's actions of disrupting roads and public transport to "shut down London" in order to bring attention to their cause, while 36% "strongly supported" or "somewhat supported" these actions.
TEK