I've not really met any Rick and Morty fans who wouldn't agree Rick is an arsehole- the whole point about his character is you have someone who is so intelligent he can overcome anything but is limited by having a terrible personality and making bad decisions which harm others. If he was a good character, he'd basically be massively overpowered and the show would get boring quickly.
You can still like Rick though, as a character.I think he relates well to certain people who either are, or think they are, geniuses frustrated by the limits society puts on them. Fans may also be envious or admire the sheer amount of freedom that Rick has- he is able to pull all sorts of shit and get away with it. Psychologically I think a lot of people would like to have that freedom but are constrained by things like jobs, their personality, culture and social etiquette.
In the end, Rick's a fun indulgence into a consequence free lifestyle, but the show's creators could well be right that that it would turn you into a complete arsehole- and in the end the vices you'd accumulate turn into your own limitations, as happens with Rick.