I feel like after a while their addiction to the organisation is conveyed rather realistically. They were famed as 'losers' and dropouts, so became obsessed with making a name for themselves, hence going after Pikachu non stop since it was the closest to a sure fire gold ticket.
After a while they dropped so bad Giovanni couldn't even remember them and a large amount of episodes toyed with them being so worn down that they considered just bailing, but then they started having small successes, little teases of reaching their goal to keep them motivated. This reached a point they were finally elite squad members, though after a taste of the big time, they started to miss the journey, they even noted how happy they were going after Pikachu and doing wacky disguises again. The goal was something to keep working to but they liked the adventure amazingly enough.
Now they tend to be given enough of a success rate to be motivated to stay in the organisation, but tend to be much more laid back about it, fine doing things on the side and just trying to make a living.