Another point of view:

https://www.merriam-webster.com/words-at-play/the-many-plura...

Octopi, octopuses, and octipodes have all been used. I personally think octopi rolls more smoothly off the tongue than either of the other two, so that's what I tend to use.

I find the arguments regarding Greek or Latin purity to be unconvincing- we are speaking neither language. We're speaking English, which is a head-on collision between the two, with Germanic trappings gluing it all together. I happily mix and mash whatever prefix, root, infix or suffix I like. If others like it and use it, success! Whether a theoretical Roman from centuries past would agree does not enter the calculation.