The startup time of Emacs is not an issue because I only start the Emacs server once and keep it running for a long time, connecting the Emacs client to it as needed. Once the Emacs server is running then connecting to it is as fast or faster than starting vim from scratch. Even restarting Emacs from scratch can be effectively instant, if you don't have a giant config like I do. Vim startup time can be slow too, by the way, if you have a lot of plugins. So, effectively, vim and Emacs don't differ on startup time these days like they used to.
As to your question about Lisp, it definitely was a huge draw to Emacs because I fell in love with Lisp and almost the entire ecosystem of Emacs is written in Lisp... and I'd certainly much rather program in Lisp than vimscript, or even Python (or any of the other more mainstream languages).
I remember coming across various things I wanted to do in vim that were pretty awkward to do because of how clunky vim and vimscript were. Lisp and Emacs just made doing what I needed much easier overall (though some things were still easier in vim.. for example, vim has some powerful features in its regex engine that don't exist in Emacs, even when using Evil). This was before neovim, so maybe it's better there, though since both vim and neovim lack Emacs' Lisp ecosystem, I doubt they'll ever be able to match Emacs in this respect.
There were a lot of other reasons for the switch to Emacs, like having deep web browser and shell integration, being able to read my email from within Emacs, and do a ton of other things from it.. org-mode was another draw.