I worked as a dev for a tech company that had MLM's as their clients almost exclusively. Some of those clients have been named in this thread but I won't list them. I helped work on the apps and website that the products were sold on.

My experience was surprisingly positive because I was shielded from the scummy side of the business. I liked my coworkers and enjoyed working on the platform. I did leave after 2 years. I learned a ton on the job which helped me land my next job which I love(and a big level up). I wouldn't go back into the MLM industry though unless I had to due to limited job choices.

I don't really have anything juicy to say about the industry, for the most part it was like any other dev job. Well the company did lay off people recently because I assume their bigger clients are running out of potential victims. Some MLM's stay forever while others burn bright and then fizzle out, so if this MLM is a new one they might fizzle out soon and you may get laid off anyways.