[joosters]

It's simple extrapolation

That's the problem though. There's a good reason why just about every financial prospectus includes the phrase "Past performance is no guarantee of future results".

Then from the 5 to 10 year span, what's going to come flying in that is going to steal their $70 to $100 billion in cash?

Why are you so confident that you can predict everything that might happen in the next 5 to 10 years?

[nl]

Why are you so confident that you can predict everything that might happen in the next 5 to 10 years?

The conservative, baseline prediction is generally "things tomorrow will be the same as today". Even if you stop their revenue growth (and there doesn't seem any good reason to think that is happening) then the parent's predictions are still basically true.

For the opposite to be true, FB doesn't just need to stop growing, it needs to shrink, and shrink very very quickly.

Can you think of a possible way Facebook could lose all their traffic in that 5 year timespan? All of FB, WhatsApp and Instagram disappearing all at once?

[joosters]

The conservative, baseline prediction is generally "things tomorrow will be the same as today"

Note that this line of thinking means that you'd never predict the rise of exceptional giants like Google & Facebook in the first place. If your line of thinking can't entertain the creation of these companies, it's unlikely to be any good at predicting their fall either.

Can you think of a possible way Facebook could lose all their traffic in that 5 year timespan?

My point is that since we can't imagine all the possible things that can or will happen in the next 5 years, the fact that we can't think of a possible way Facebook could lose all their traffic becomes meaningless and useless as a reliable source of predictions.