How are startups actually handling cybersecurity? I will not promote

I've been researching how founders are handling cybersecurity, especially with the current speed of development with AI. For those of you building companies, I'm curious: What are you using for cloud infrastructure and data storage (AWS, Azure, GCP, Supabase, Vercel, etc.)? Do you use any security tools, or mostly rely on the defaults provided by your cloud platform? At what point did security become something you started thinking seriously about? If you're using tools like Security Hub, Wiz, Prowler, Check