Well, this website https://usinterestrates.com/corporate-bond-yields says that currently, B-grade bonds go at around 8.5%. So bonds paying 10% would be below B, pretty much in junk bond territory https://www.investopedia.com/terms/j/junkbond.asp .

So maybe it's not high risk enough for you, but it is definitely high risk enough for the market.

But the best approach is just comparing rates. Go to https://archive.epa.gov/epawaste/nonhaz/municipal/web/pdf/bo... , and you will see a huge list of companies whose bonds are classified by armies of analysts as "less risky" than these 10% Anthropic bonds. Is Anthropic less risky than AT&T, or BP, or Firestone Tire & Rubber Co? The market says "no".