There is a place for re-buys and add-ons, but some players miss use it, I once played in a £50 Tournament that had unlimited re-buys for 4 hours and one particular individual bought back in 6 times and still never made the pay-out's. Costing him a total of £350.
I immediately thought that this Guy had a serious problem and needed to be told how stupid he was playing , but I certainly wasn't going to tell him as I had taken him out Twice! and made a healthy stack out of him.
In another Free-roll on-line there was a ruling that if busted out early you could re-buy or add-on for 10 Cents, I was fortunate to make the money before the Re-buys finished and added-on to ladder higher in the pay table, I didn't need to add-on but felt as it was a free-roll there would be players who didn't have the funds to add-on and was proven right.
I made the final table and won quite a bit more than the 10 Cents it cost me to add-on, Some might think this was cheating but it was in the rules before the game started, and it was open to everyone if they had the funds to do it.
You have to weigh up the Pros and Cons of buying back into a Tournament and if you can afford the extra buy-in amount? It is not always in your best interest to do this depending on how many players are still in the Tournament and how many BBs you will be starting back with, so do your Maths before jumping back in.
When the fun Stops, STOP!
(or Re-buy

)