> It is probably at least 100,000.
no need to guess. the second quarter results for alphabet inc says 89,058 employees.
I would like to challenge you on your belief - YouTube offers an Ad-free mode and the subscriber numbers are still considered to be abysmal , considering that it has 1B+ total users. What makes you think charging $5 to $10 per month would retain enough users?
Moreover, Google made ~$15B in Q2 2018 in USA alone. 86% came from ads, so let's assume Google made ~13B from ads in the USA in Q2-18. Even if we were to assume that each of the 240M internet users in the USA pays $10/mo to Google (an obviously false assumption), that is still only $7.2B for Q2-18, or half the revenue they are making from ads.