It works with most websites, it syncs my bookmarks across computers, lets me reuse my existing Google account instead of needing to make a new one, and I really don’t care about my data going to Google because I already give up my data in exchange for free services (which feels like a win-win).
It is detrimental to your privacy, which is why I compare it to chain smoking. You may not care about your privacy that much, because you don’t believe it affects you that much, and chainsmokers tend to downplay the detrimental effects of smoking too, until it finally hits them with disease.
Now what would be the privacy equivalent of disease? Maybe one of the thousands of partners google sends your data to has a giant databreach, and now your entire browsing history is public knowledge. “Big deal” you might say, until you remember when you looked up symptoms of chlamydia to confirm whether or not you might have it, or when you searched for “furry self suck videos real”. Suddenly you also become a victim of identity theft and they use your identity to groom little girls, or scam older people.
This is a worst case scenario, yet it has already happened over and over.
A less worse scenario is you get advertisements for chlamydia treatment, and it makes you slightly uncomfortable. Or maybe you look for vacation spots, and the prices are automatically raised to be just enough for what yout would be willing to pay, but still more than the original price.