Yes you can cook chili too long especially when you're cooking your chili on the stove in a pot.
Never leave a pot of chili on the stove cooking when away from the home or asleep as the chili will burn and there can be a fire.
If you want to cook chili overnight you should put the chili mixture into a crock pot and cook the chili in the crock pot which makes it easier to cook the chili without having to be around to tend to the cooking of the chili.
When cooking chili it's best to cook the hamburger first and then mix it together with the chili seasoning and other ingredients.
Then slow simmer the chili on the stove until it's warmed up.
To cook the chili without browning the meat first mix all the ingredients into the stove top pan and then slow simmer it for 1 hour and 30 minutes.
You need to also stir the chili so that it does not burn.