How do we know? Because 10 teams win 66% of the games in Omaha.
I looked it up to verify and your statistic means nothing.
Why?
First, because 10 teams is an arbitrary number. There were 32 different teams that won CWS games in the last decade (2008-17). Why 10? It has no significance whatsoever.
These are the 10 schools.
South Carolina - 15
Virginia - 12
LSU -11
TCU - 11
Florida - 11
Vanderbilt - 11
Arizona - 10
UCLA - 9
North Carolina - 8
Texas - 7
The examples of randomness are endless
just in these schools listed.
South Carolina won all of those games in 3 successive years. They were on a heater. They didn't even reach Omaha in the two years prior in the sample (2008-09) and haven't made it since (2013-17).
LSU won 9 of their 11 games in two years (2009 and 2017). Same with Vanderbilt.
Florida won all of their games in 3 years (2011, 2015 and 2017). Guess what else they did in 3 seasons? Go 0-2 BBQ! (2010, 2012 and 2016).
UCLA won 8 of their 9 games in 2 years.
Arizona won all 10 of their games in 2 years.
Their only CWS wins since 1986.
Texas stunk for most of this period. They had more missed Regionals (3) than they did years with a CWS win (2)!
Predictable? Please.
Going back to the initial point. Why stop at 10? Why not 11?
The 11th team is Coastal Carolina with 6.
Of course all 6 of those wins came in one year (2016).