Qur'an 8:41 - And know that whatever spoils you gain, to God belong its fifth, and to the Messenger*, and the relatives, and the orphans and the poor ......*
They say that, "Well, Muhammad can't be a real prophet because he acquired material wealth through Qur'anic legislation as seen in the above verse." I'm not saying these people are necessarily right, but pointing out that the moment you benefit materially from your activism, it becomes a blight on your public image.
Also note that people who make money from activism against some 'hate group', wouldn't want those hate group to disappear. Would they? Probably not. After all, the source of their livelihood depend on the existence of such hate group. They need to sustain the 'hate' in order to feed.
Lastly, there is censorship. There are people who won't like your activism, no matter how polite and civil you present yourself. And they can get you censored through accusation of blasphemy, hate speech, misinformation etc. Freedom of Speech is a scam, it never really existed.