Watch carefully what happens in the parable. The storm hits both houses. The same rain, the same wind, the same flood beat against the house on the rock and the house on the sand. The storm is not a punishment for building on sand. The storm comes to everybody. France notes that the imagery here is the sudden violence of a Palestinian wadi, a dry riverbed that becomes a raging torrent when the rains come, sweeping away anything not anchored to bedrock. Keener and Osborne highlight that Matthew piles up the assault, rain and floods and winds together, a total testing of the house.
So if you follow Jesus, do not expect the storms to skip your street. Jesus guarantees the opposite. The rain is coming to your house. You may not be in a storm right now, and if so, praise God. But the storms of life are coming with more certainty than any weather forecaster could ever promise, because Jesus himself says they are coming. The difference is not whether the storm comes. The difference is what the storm reveals when it comes.
This is the second great truth of the passage: the storm does not build your house, it reveals it. In dry weather, with no rain, you cannot tell the two houses apart. Both have walls, a roof, and doors. On a sunny day, anyone can look like a Christian. Any creed or philosophy seems to work when the bills are paid, the marriage is good, and the diagnosis comes back clear. It is only when the water rises that you find out what you were actually standing on the whole time.