> adguard is free [...] open source adblockers like ublock origin lite [...] and some other one

Yet not "every user has switched to these free products". Apparently the consumers don't feel the same way as yourself, or they are not aware of those options (marketing costs, too). Hence (quoting myself):

> A product justifies its price tag as long as people are willing to buy it at that price.

I'm not a 1Blocker user, but 1Blocker definitely doesn't have to price match anyone else if their customers are happy to pay despite there are many free options.