Ok, let's say 25% growth over 10 years. That is a factor of 9.

9*$50B = $450B yearly revenue.

What could be the margin Alphabet makes from that? Last quarter, Alphabet had $100B revenue and $35B net income. So 35% margin.

$450Bx0.35 = $158B

What is $158B in annual profit worth? Currently Alphabet's p/e is about 30. If we take that, it would be $158Bx30 = $4740B. So around $5T.

If we are heading towards the creation of $5T in value via cloud revenue, investing $100B per year to build it seems not particularly high to me.