$TSLA Semi is a great product. It's just not a great product for Tesla right now.
The constraint is batteries. Cybercab, Model Y and Semi all draw from the same limited supply of 4680 cells.
So the question isn't whether Semi is good. It's what each cell earns.
Per cell, Semi makes roughly 20 to 30% less than a Model Y, and far less than Cybercab.
When supply is capped, you don't allocate to demand. You allocate to margin. Every cell in a Semi is a cell that didn't go into a higher-earning product.
That's why Semi won't scale anytime soon, even though the market wants it.