Only he knows the truth, and I think the reason he doesn't want to share and also doesn't want his wife and kids to know about big wins is, because in the end the winning money will still be used.
And maybe they are afraid of wasting money on unimportant things or spending it in the wrong way because they know the bad nature of their children and wives, so keeping it a secret is the best option. Dan will continue to use them when needed and for the long haul because he knows he has a long way to go in life and that is what he is worried about.
and he does a deed that I think no one else does, and I judge this in my opinion he is a good person and has good intentions for his family.