In the material world, almost everyone strives towards gaining material riches, but the vedic scriptures say, that material riches are actually like poison to non-vaishnavas.
A materialistic person is already in ignorance and if he gains more materialistic things it will actually increase the ignorance, increase attachment to the world, create more confusion, create more problems and the biggest danger of all, it will destroy spiritual progress.
Only a vaishnava is able to handle material riches properly, because a vaishnava knows that everything comes from god ( Vishnu), he will use those riches only to worship god. Also only a vaishnava properly knows about the dangers of material riches, which is that it threatens the spiritual progression, which is the most important thing in life, therefore a vaishnava will sacrifice material riches to reach the highest goal in life, where a non-vaishnava would do the opposite and sacrifice the spiritual progress for material riches.
This means the more material riches you will give to a non-vaishnava, the more he will sink into darkness and evil and the more material riches you will give to a vaishnava, the more enlightened and virtuous he will become and not only him, but also others around him.
In the vedics there is the example of milk and the snake, milk is a virtuous food, but if you feed milk to a snake (a demon) it will just use it to produce poison.