Completely Misleading Thread Title. The poll does not indicate that 34% of young adults in America believe the Earth is Flat. You should learn to read polls.
There are 5 response groups.
Always Believed Earth is Round
Believed Earth is Round, but is now skeptical
Believed Earth is Flat, but is now skeptical
Always Believed the Earth is Flat
Unsure
In the age group of 18-25:
66% have always believed the earth is round.
9% believed it was round, but are now skeptical
5% believed it was flat, but are now skeptical
4% have always believed the earth is flat
16% are unsure
The 16% unsure does not make that group believers that the earth is flat. They don't count toward either count, so you can't include that in your count of believers in flat earth..
For the 5% that believed it was flat, but are skeptical, you could count them as flat earthers, as they believe but are skeptical of the model.
For the 9% who believe round, but are skeptical, you can't count them flat earthers. Just because one is skeptical, doesn't mean they believe in the flat earth model, or completely reject the round earth model.
At best, if you include both of the skeptics, that would be 18% that believe the earth is flat or may not be round amongst young Americans.
In reality, you have 9% of young Americans that believe in flat earth, with 5% being skeptical of that.
On the other hand, you have 75% of young Americans that believe is round earth, with 9% being skeptical of that model.