Because him taking over a house gives him access to resources which he can use to build up strength, unchecked, and before you know it, the state next to you is involved in serious tumroil that affects your job, getting certain products, and so on.
And next thing you know, people who directly work for that drug dealer are all in your states government, and your way of life is slowly starting to get worse, and the only option you have is either go along and be constantly afraid, or revolt and risk of losing your life.
If you dont think it can happen, i envy your ignorance.