I can think of a couple decent reasons I think yes:
- Assuming you still have a life, you are still generating new data. Think about how someone who knew you 5 years ago but hasn't seen you since would probably not know much about you today, specifically regarding the day-to-day stuff companies use for ads.
- If you think what data companies are doing is wrong, then you could start caring about privacy just to send a message.
- If you live in the EU you could use GDPR to request that they delete your data. I don't know if Apple and Google have been known to comply with GDPR but it could be worth a shot.