It's possible you're drinking the wrong gin and not all tonics are equal. When I still drank alcohol G&T was the weapon of choice. Tanqueray (spelling?) was lovely but Gordons was good and of course it has to be strong.
The terrible stuff we got in Ghana in teh 70's was pretty raw - I visited the factory once and saw the drums of alcohol they used. I didn't see the drums of flavouring
I tried quite a few gins, and now a few different tonics. Nothing yet I can stomach, although there is a bottle of Tanqueray Rangpur on my desk. Maybe after I photograph it I'll find out I like it.
To each their own. I can drink Tequila like water (not sure if that is a good thing), but I know quite a few who hate the stuff.