Let's do an extreme example to show the effect of the reverse split on shareholders.
Let's say you owned 50% of BUDT that Ealixir was merging with. You would own 7,798,428 shares out of the 15,596,856 outstanding shares.
After this deal you would own 311,938 shares out of 36 million outstanding. That would be 0.9%
We all knew Ealixir was merging with BUDT so BUDT is Ealixir. So after this deal a 50% owner became a less than 1% owner. That's why the price tanked.