unless you think it's a risk-free asset

And unless your risk aversion is zero. Which more or less holds true for me. (Aka, playing a game of coin tossing where head wins a dollar and tail loses a dollar does not make me uncomfortable).

Otherwise it depends on:

1) Your risk aversion

2) The percentage of your portfolio you intend to invest into Tesla

3) How correlated your portfolio is to Tesla

If you only invest a sufficiently small amount (compared to your overall portfolio) into something, then the overall risk of your portfolio will go down. No matter how volatile that something is. So in that case, there also is no need to discount future earnings except for expected inflation.