Father Cantalamessa, published by Zenit:
However, the parable does not say "a man sold everything he had and started to look for a hidden treasure." We know how such stories end: One loses what one had and finds no treasure. These are stories of dreamers, of visionaries.-- from Seek the Treasure That Awaits, Gospel Commentary for 17th Sunday in Ordinary Time, By Father Raniero Cantalamessa, OFM Cap
No, man found a treasure and, because of this, sold all he had to buy it. In a word, it is necessary to have found the treasure to have the strength and joy to sell everything.
Leaving the parable to one side, we must first find Jesus, meet him in a personal, new and convincing way. Discover him as friend and savior. Then it will be child's play to sell everything.
It is something that will be "full of joy," as the proprietor mentioned in the Gospel.