Eh, I don't think they would have expected most people to buy them anyway so that doesn't seem likely. If we're talking about how much money a player could have saved from buying one (e.g. one lifetime OBC membership = the price of 3 annual OBC memberships) then that's where they might have seen what was happening and gotten rid of it.
Easy answer: If most people would bought lifetime builders club, then no one would buy a membership again and people would start to lose money, but that could not happen because back in the day, THERE WAS A BIG COMMUNITY, so my conclusion is that no one bough it or that they do not wanted to More than 75% people buy and not buy any more robux or another membership so they would go bankrupt.
Stop saying that "Roblox is running low on money" or whatever, because they're not. They would be, however, had the feature stayed. Roblox needs billions of dollars just to keep all of their thousands of servers running. On top of that, there's also devex and the fact that some developers are cashing out roughly 1 million dollars every 1-2 months. Please, before throwing the classic "roblox is greedy" or "roblox wants money", think about your response. They're not greedy, they're just doing what they need to do to keep the company alive.
It is most probably because ROBLOX was getting famous and the servers couldn't handle it if everyone was purchasing lifetime. They need to run their server room too. Not to include the bills: Electricity for the ROBLOX HQ (huge building, huge bill), heat, and other bills. They would have to shut down the game if they gained so low income. You wouldn't want that would you?
Probably due to the rising of popularity on youtube so youtubers tend to buy things like that to get more fans therefore they were losing profit cause the amount it costed costs the same amount as 3 months of OBC today.
The problem is that, Roblox would be making a lot more money if they just raised the price. Older players, don't come back to roblox and because you can't refund the Lifetime purchase, players would be buying something, that they're not going to you use. It's like buying those jumbo candy bags, and not being able to finish it/or getting tired of it. However if you get small candy bags, and then get tired off it, you won't be wasting as much money