Its better to save it and earn small rewards for unused invites that to issue it and get nothing from failed invites.
Starting March 25 hardfork all human will get 2 invites
I'm saying this since the last update, stop sending the invites for free! It is not worth it, sell them and stay on the head of the buyer, be sure that he is interested. Of course, don't overprice them, sell them at a decent price.
Right now at least with all the activity in the telegram invites requests, you can't know anymore who is real or who is fake. Do they just want an invite to see how the wallet looks like? Maybe they believe it has different features or that they can mine isntantly!?
There has to be created a treshold like XRP is having for each new member joining. This way we can also help a lot the coin on exchanges. The ammount needed to be a candidate should be burned.