Hellow @steemit-legacies! Thank you so much for dropping by. :)
These people who send reactions are into this kind of service. They decided to take part on this service so they well knew that their accounts will be used to send likes or reactions. We can even do real comments basing on the content of the post itself.

To put it in a simple term, we follow, comment and like each other. If they did not want their account to use, then, why are they still on our site, gathering likes from others? They are aware of the terms and services of our site so it is understandable that they agree to it while they are active in using the site.

Sending 10k or more reactions may take days but it is accomplishable.