Was being in The Rat Pack a blessing or a curse?
Or both?
Because Frank was The Chairman of the Board, the Boss, the alpha male, and he expected all the other mebers of the Rat Pack* to do his bidding and dance to his tune. If he ever considered that a member had "betrayed" him in any way, he'd kick them out of the pack and destroy their career the way he famously destroyed Peter Lawford.
So frankly, the rest of the Rat Pack must have been afraid of Sinatra, and kept in line through fear. Which must have been as stifling as all hell, if they bowed out of the gang there would be hell to pay.
* Dean Martin excepted. Martin wasn't afraid of Sinatra, he was a big star in his own right, and he was one of those self-contained people who was always slightly apart from the group. He didn't *need* Sinatra, even if he liked him and enjoyed his company.