It depends.
Uturn describes company sales, which probably has at least a base salary, maybe supplemented with commissions (my father had a role that combines both what Uturn describes as sales and his own job, so my father was the front man and the designer, no commissions).
Sales can be stressful if you are dependent entirely on the commission, like cars, homes and boats, because your pay check is determined 100% by whether or not you make a sale. This works great in a down turn for those of us who are in sales as a side hustle, as all the income dependent folks move on to something else.
In my experience, the real stress of sales commission are the other sales people who are stressing themselves out. All sense of decency and fair play goes out the window. I have always known that my colleague kind of resents me showing (and often selling) his listings, but the other day he said he was trying not to show my listings. What? No! We are supposed to be working together, for the sake of our clients. Sell the d@mn listing, even if it cuts my commission in half!! Even though he is in a base salary position, my brother in law has a similar issue with one employee who keeps "forgetting" to forward calls to other sales people when he should.