B2b lead generation is impossible!!!!

I am a co-founder of a startup and I am trying to do lead generation for a month now. And i tried a lot of things i tried Apollo, lusha, databases none is working for me.

I even tried a osint tool for information gathering but that even didn't work. Can anyone help me or suggest me where i can find the database atleast numbers email which i can use for cold calling or outreach.

My niche is insurance agencies.