You don't need a license or formal training, but the reason for that is not because there is some right to fly ultralights. It is because the FAA rules specifically give permission to fly ultalights without a license or formal training. See 14 CFR 103.7 [1].

[1] https://www.law.cornell.edu/cfr/text/14/103.7

Actually, that's a very good point. There are some important restrictions regarding airspace but there are legal ways to get up in the air by yourself without any training

Good call out there

The tenth amendment would beg to differ!