If there’s ANY link with recreational drugs, they haven’t found it yet.
There are very few lifestyle factors that have been shown to have any influence at all on the chances of someone developing MS.
Smoking, unfortunately (i.e. just tobacco), is one of them - but that doesn’t make it a cause of MS, only something that probably adds to the risk, IF you were predisposed already.
Where you live/grew up is also a factor: in general, MS is much more prevalent, the further you get from the equator. An obvious thing that decreases the further you move from the equator is sunlight - and hence, Vitamin D - produced mostly from sunlight. So the role of Vitamin D deficiency in the development and possible severity of MS is a hot research topic - it’s looking as if Vitamin D - or lack of it - certainly does play a part, although the exact mechanism isn’t yet understood.
There are also at least 40 known genes that are associated with an increased risk of MS. But of course, this is not a “lifestyle” factor, it’s luck-of-the-draw; you get what you get!
Having been lumbered with an unfortunate set of genes, and living in a largely grey country, in the Northern Hemisphere, are much more likely to have played a part than anything you actually DID.
NICE guidelines even say the patient is supposed to be told it’s not their fault, to stop this endless: “Oh God, what have I done to myself?” line of self-torment.