Why did God give us the chance to ask anything we want when there can be a downside to it?
We already enjoy an incredible number of blessings; the very fact of existing is a blessing that cannot be repaid. It makes no difference to God to increase these blessings for us; if we submit and constantly seek His guidance then we will be safe from the downsides.
It is natural for humans to desire to have more than they already have. God does not tell us to completely suppress this desire since it is a morally neutral thing. It pleases God to give us blessings since it is a place where His attribute of the Most Generous is expressed.