I was wondering about the statements here (2015) and they not only hold true but seem even higher for .com use in 2019:
Per: http://paulgraham.com/name.html
> 100% of the top 20 YC companies by valuation have the .com of their name. 94% of the top 50 do.
Top 20: 100% (2019)
Top 32: 100% (2019)
Top 50: 98% (2019)
Top 100: 95% (2019)
(Twitch #21 actually owns twitch.com ... xendit #53 owns xendit.com .. cleartax owns cleartax.com ... quero owns quero.com )
Ref: https://www.ycombinator.com/topcompanies/