Have had a cavity in wisdom tooth for over 5 years. No dental insurance, so left it. Could this cause other health problems to overall health?

Absolutely. That rotten tooth will at some point abscess, which can cause the infection to drain under your tongue and potentially close off your airway. Insurance or not, you need to take care of your health. Contact your local dental society for low cost options.
Yes. Yes, as the cavity progresses it may lead to nerve issues in that tooth and possible infections/abcess with that tooth as well. An infection in the mouth = an infection in the body. I would have it evaluated.

Related Questions

Cavity on one Wisdom tooth. Has been there for years. Can this affect other teeth or overall mouth health? Waiting for insurance to cover it. No pain.

Yes. A wisdom tooth can cause tooth decay and/or periodontal disease in adjacent teeth. See the wisdom tooth specialist - oral surgeon - for best advice. Read more...
Maybe. The reason to have your wisdom teeth removed is they are difficult to manage as we mature. Since you have have "long time" decay your options to have your tooth restored with a filling maybe limited to extraction. Microbes swim in the liquids of the mouth. They have the potential to cause decay anywhere they successfully colonize on the tooth surface. Read more...
Long Term Caries. At this point, the tooth most likely needs extraction. The decay may have spread to the distal of the second molar, necessitating additional treatment. Bone loss around the tooth may be present. Surgical extractions may still require out of pocket payment, regardless of insurance. Pain may also begin at any time. Read more...