The advertisers are paying for the opportunity either way. Clicks cost them more money than just displaying the ad. Useless clicks cost them money for nothing.

No, because it devalues their click through, as no sales will result from those clicks.

It's kinda like printing money, there's more of it, but the overall value hasn't increased.

In the short term, I would think so.

In the long run, it makes it less appealing for companies to advertise, because they would have larger costs while having less sales. That, in return, hurts Google as advertisers don't want to pay as much anymore. If 80% of all users used this extension, advertisers would have to pay more than ever, while having only 20% of all users can be reached (simplified, of course).

Or in short, it's designed to hurt the system as a whole, not specific companies.