Google was made possible by US antitrust turning a blind eye towards Google's acquisition of DoubleClick and YouTube. Considering Alphabet is dominating both search and ads and also offers services via searches, the EU commission already hinted at a breakup as a viable measure to lead the web out of its misery.
Google's market cap was already at over $100B with billions in revenue and hundreds of millions in profits when it bought DoubleClick and YouTube.
So while those were big aquisitions (Around $3B and $2B) they only accelerated the process of Google turning into the web's central player. It was already set in motion before the aquisitions.
[1]: https://ec.europa.eu/commission/presscorner/detail/en/ip_23_...