Question

My brother bought a business in a very specific area of clothing.
Thank God, he is making a profit. [There are not many competitors in this particular market.]
Anyone who buys this specific product replaces it with a new one every year or two. It does not last longer than that.
He came up with a unique solution that preserves the product and greatly extends its lifespan.
The advantage: he is unique in this [it is a secret], and he could sell the product at a higher price with the promise that it will last longer.
The disadvantage: instead of replacing it every year or two, people would replace it only every two to four years. So the damage to him and to the other merchants would be enormous
[apparently a reduction of sales by 50%], and in return he would not be able to ask double the price [the product is expensive as it is], only a little more.
His question: is he obligated to provide this service and offer something new in the market, thereby hurting 50% of his income? Or is he permitted from the outset to be like an inventor who suppresses his invention?
 
Respectfully.