Hmm, I don't think the past is a good predictor of the future in this case.
Maybe everyone likely to leave reddit for lemmy already has?
With the influxes that have occurred in the past I think Lemmy has retained about a third of the MAUs contained in the spike. It's not nothing but I think it really underlines my point that Lemmy just isn't a viable alternative for a lot of reddit users. The network effect might be responsible for some of that, but not all.
Also, as time goes by there are more corporate backed alternatives, like threads.
I hear what you're saying, but I think my point is that it doesn't require "logic" it's just basic threat aversion.
Perhaps the missing link is that people don't realise that Musk's interests are not aligned with their own.