The person who is not thankful to Allah for cold, pure water; will not be thankful to Him for a mansion or a luxury car.
The person who is not thankful for warm bread will not be grateful if he suddenly becomes blessed with luxury food items, because an ingrate sees a little and a lot to be the same thing. Many before us have made binding promises to Allah that, if He were to give them blessings. They would in turn be grateful and give charity.
(And of them are some who made a covenant with Allah [saying]:
He bestowed on us of His Bounty we will verily, give Sadaqah [Zakah and voluntary charity in Allah s Cause] and will he certainly among those who are righteous. ‘Then when He gave them of His Bounty, they became niggardly [refused to pay the Zakah or voluntary charity], and turned away, averse.) (Qur’an 75: 7 6)
Every day we see people of this sort, people that are mentally distressed, empty on the inside, and bitter towards their Lord because He did not give them more. They feel this way despite their good state of health and in spite of the nourishing food that sustains them daily, not to mention all of the basic needs that they have. They are not thankful for these things, nor are they thankful for the free time that they have. What would then be the case if they were given castles or mansions! Indeed they would deviate even further from the path of their Lord and they would increase in haughtiness and disdain.
The one who walks barefooted says, "l will be thankful to my Lord when he blesses me with shoes." And the one with shoes postpones being grateful until he gets an expensive car. We take blessings cash down and are thankful on credit. Our wishes from Allah are never-ending while we are slow and lethargic in applying His commandments.