Pains behind gift giving

My brother, a retired US Navy Chief is loved by family and friends and coworkers alike for his hard work and his sense of humor. However, when he came to the US in 1977,  he was not very confident about how he would survive as he had not finished his college. Our Mom used to worry about his future as well, you know how people worry about a man supporting his wife and kids. Then he joined the Navy and soon after that he met a very nice girl. She became an inspiration for him. He pulled through the verbal abuse that comes with the basic training and the physical hardships as well. They had a simple wedding and he would sometimes take her on his ship and sometimes leave her home with her parents. When they had a beautiful baby girl, he did the same thing. A year later, they had one more cutie. Now a father of two little girls, he would go abroad sometimes leaving them with his in-laws and somtimes with our Mom and very rarely taking them with him. Now that he is retired, he spends a lot of quality time with his wife and his daughters who are in their teenage years, teaches them how to stay away from troubles and the importance of education. However, when it comes to spending money, anyone who knows him thinks that he is spoiling them. He says that when his wife and kids ask for something, no matter how expensive it may be he will not say no. His logic is that they were very patient when he was away and very supportive when he would be too tired to do anything fun with them. He always says that what they gave him is more than he could ever give them, so he tries to buy them what ever they want.
When I come home from work and talk to my husband about how people are spending money, he tells me that I do not know what they could be going through. He tells me to look at my brother and understand people's pain behind their gift giving.