Indeed it is marginally safer for one to simply use a strong adblocker and protect themselves. And it is also safer to stay at home rather than to attend a protest. But safety is not the only concern. Using an adblocker does little to change the status quo. AdNauseam, and the obfuscation strategy in general, instead presents a possible avenue for collective resistance; a means of questioning and perhaps, eventually, changing the system. But this is not for everyone. If your goal is primarily self-protection, it may not be for you...
So they're aware of the fact this is worse at protecting privacy than a simple blocker, and equally unambiguous about their objectives being to change the status quo by damaging ad networks' business models. And yes, they've calculated the direct cost of some of those clicks too:
As the precise cost generated by clicks is not visible to the client, AdNauseam calculates an estimate using an average value of $1.58 for each clicked Ad.