Aside from Google selling you ads,...

a private personal ai could function to help you maintain your goals. It could keep you on time, schedule appointments and orders, monitor your sleep and diet and exercise, monitor your stress and health, ensure folks remember to take their medications, coach you on focus, help build and maintain project plans, etc.

The "second brain" concept isn't new, and is somewhat related. AI could help leverage your personal content into triggered actions to improve your day.

If a truly private ai assistant existed, and you could train it on the operational parameters that matter to you, it could help a lot of people. Especially those who are too too busy in life, or have memory or executive function issues.

If course you could do this now, with manually written events and alarms/reminders, but by establishing an "actor" to ride along with you and help create and report stuff you care about, you can help people with things they'd otherwise miss.

I personally believe private, open sourced solutions are realistic in the nearish future, but most will sign up for some sort of Google suppositor-ai