[michaeldhopkins]

Two possibilities:

1. You didn't say your third paragraph or didn't say it loudly/clearly/often enough. If this is the case, be more clear about it next time.

2. You said it but they disagree with you. If this is the case, maybe they are right, or maybe you need to find a way to prove the adaptability. Keep in mind everyone thinks their startup is adaptable to a huge market to a degree. You need to be relatively more able to develop a huge market than other interviewees.