Obedience usually guarantees success and prosperity. In Deuteronomy, the blessings and curses mentioned are part of the covenant between God and Israel. If Israel obeyed and kept God’s laws, God would bless them with success and prosperity. In Deuteronomy 1:32, Moses reminded the Israelites of their refusal to believe God. The Israelites were punished, because they refused to trust in God. When we refuse to trust God, we will not be successful.
Believing in God has its rewards. Suffering may come to those who are righteous. But, if we are faithful in our obedience to Him, His way is always better. Obedience to God guarantees spiritual success and prosperity, but does not always guarantee absence of physical problems.