Chance to sell business. Should I do it?

Bought an old antiquated baby boomer run company 5 years ago for 5x $500k in EBITDA. Distributed $1,000,000 after tax over the last 5 years. Have chance to sell for $20 million minus taxes and fees. Debt has all been paid off. Seems weird to be selling after only 5 years, considering could have more growth, but will also be a huge win. Thoughts?