I think other clubs have been talking exactly the same thing about our club, or at least in the first 5 years or so: "mercenaries who's heart ain't really in a relegation fight".
The thing is, there's a grey area in that: some players will come purely because of money, some because they'll have a higher chance of getting some trophies (comparing to their current club), some because they will player with better players, etc. and behind all most those (good) reasons, we can't deny that money always play a big role!
And people may move because of "money" motivation, but if the club can bring good coach, good environment, good culture, etc., they people will stick and build up from that as you mentioned. So yeah, "money" is sometimes a good reason for moving too.
Therefore, I think it's no need to concern about "money" motivation, not to concern for other clubs, and not for our club too. It's always a part of our life.