And I bet you use Google's other services for free.
Or they can drop the adtech business or spin it out as a separate company. But either way currently there is no way to fairly deal with ad tech companies with thinly veneered “free” services on top.
Spoiler: $0. Your data is not worth anything.
1. Your kidneys, or heart, or any vital organ.
2. Weapons grade Plutonium.
3. Falcon heavy.
4. A single grain of rice, 100 million times.
What you are saying implies “we don’t have a good marketplace for user data”, which is pretty obvious. But I have no idea how “thus it is worth nothing” follows from there.
Your individual data is worthless. Data is only worth something in aggregate.