Grammarly advertises quite agressively, at least to my demographic. I pointed out to my brother, who installed the addon, that they necesarily must be making mo

Grammarly advertises quite agressively, at least to my demographic. I pointed out to my brother, who installed the addon, that they necesarily must be making money off him, probably by selling his data. He said he didn't care. Taking a step back, why should he care? His data is completely free for him to hand out. If he gets an effective product in exchange, why shouldn't he take advantage of it?