If you drink a lot of beer, you're likely to get drunk. Therefore, the more beer you drink, the more you'll drink, resulting in a loss of inhibition, which translates to a higher beer intake. That's not positive in a regulatory sense or a feedback loop that reinforces. A common positive feedback cycle that can occur in your lifetime is dependence on a substance.
For example, if you drink a few alcoholic beverages in a short time, your blood alcohol level rises rapidly. While this level is increasing, it can be a pleasant race. However, a positive feedback system amplifies the original input in the system. In Jordan Peterson's book 12 Rules for Life, he explains positive feedback loops using a musical reference.
A squeak that is often heard when someone is speaking into a microphone or in a band is an example of a positive feedback loop. The microphone (Receiver) sends a signal to the speakers (Control). The speakers then output the signal (output). The signal can be picked up again through the microphone and, if it's too close or too loud, the signal continues to amplify to a loud tone.
Peterson argues that it is these positive feedback systems that are at play when it comes to mental illness and addictions. Peterson uses the example of alcohol addiction;.