Yes it's a misconception. Their profit margin on cars is consistently over 20%. They have large overhead costs that are more or less fixed like R&D that get amortized more and more as sales go up. They have massive net free cash flow every quarter even while building out new factories that will increase production capacity by 50% every year for the next several years, further increasing economies of scale and operating margins.
You and GP are arguing two different things and are both right.
GP's claim is that Tesla would not be profitable without regulatory credit sales: this is true. Tesla's profit for 2020 is $721M and its credit sales for 2020 are $1.58B, just over double. It's fair to say that, were those credit sales to fall to zero, Tesla risks losing its profitable status. Here we're effectively discussing net profit margin for the company as a whole.
Your claim is that Tesla's automotive gross margin on car sales is 20%. This is also true, but only includes COGS (Cost of Goods Sold), so car parts and assembly costs. It does not include other expenditures such as CapEx or R&D. 20% sounds great (and it is), but when we look at the net profit margin, $721M of profit on $31.54B of revenue gives only a 2.2% net profit margin which is not as impressive.
It's therefore rather unfair to say that GP's claim is a misconception, it's actually perfectly true.
