Is this fraud? my friend told me about her working with an online friend to be their "picker"

I'll describe it as best I can from what I remember, I feel like her "friend" (Zack from now on) is taking advantage of her little knowledge of BTC. (I don't know either). Basically Zack's clients send her money through zelle or venmo, she buys byc on coinbase or venmo then sends it back to them for a cut of the cost, maybe 10%. This feels like tax fraud. Anyone know?