If you don't get an open bite corrected how can that affect you?

It can have: effects on speech, swallowing, breathing, chewing, appearance, long term gum health.

System: Teeth & jaws are genetically designed to meet & function in a specific manner. Failure to fit &function properly, a malocclusion, can cause excessive tooth wear, tooth fractures, speech defects, improper chewing/swallowing, aberrant muscle function, TMJ dysfunction, loss of tooth supporting bone and gum tissues, and altered appearance. See an Orthodontic Specialist for exam (usually free).

Gum disease: If left uncorrected open bites can become potential periodontal problems (gum disease) and a consequent loss of teeth.