I don't think this is a problem as long as you are leading a well rounded and fulfilling life. If the ONLY thing you get enjoyment out of is BDSM play, then maybe you do keep searching for more. But life happens.

Master and slave defines our relationship, and is who we are at the core. But at the same time we have busy lives and have share a lot of other activities and interests outside of the bedroom. There are times that you are excited just to be able to find time to have sex, and are not so worried about doing something "new".

I would compare it to roller coaster enthusiasts, as they are in it for the adrenaline rush, just like a lot of S&M players are. Sure, when a fresh new roller coaster comes out it is super exciting and they all travel accross the country to ride it... but it is not like new ones come out every week. It is still a lot of fun to go on rides that you have been on before.