I'm actually curious about this. So, if you exclude "sell to a greater fool" as a reason for buying, and an estimate of future cash flows as a reason for buying, what is the reason for buying Tesla?
I just want to understand what you're getting at.
Think of it this way - can you estimate TSLA, TWTR, or FB future cash flows? If you could, doing so requires ways of thinking that are totally different from value investing in say, a net-net. How many value investors do you see in these names? How many times do you see someone say "I'm going to put this in the too hard pile". Markets are pretty much segmented because investors fish in different pools.
On paper, growth is a component of value, in practice, it is a different game. Are all investors in these firms expecting to sell to a "greater fool"? Those are momentum, not growth investors. Does that mean there is no legitimate investment case for investing in FB?