Here "rich" is a nominal adjective. It can be stated as an adjective. AT: "Tell those who are rich" (See: [[rc://en/ta/man/translate/figs-nominaladj]])
"all the things that will make us truly happy." The reference here may include physical objects, but it more likely refers to states like love, joy, and peace that people try to obtain by means of physical objects.
Paul speaks of spiritual blessings as if they were earthly wealth. AT: "serve and help others in many ways" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here Paul speaks about God's blessings that he gives in heaven as if they are riches that a person is storing away for later use. And, the certainty of these blessings that people will never lose is spoke of as if they were the foundation of a building. AT: "it will be as though they were storing up for themselves many things that God will give them" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This recalls the sports metaphor of [1 Timothy 6:12](./11.md), where the prize is something that the winner can actually hold in his hands. Here the "prize" is "real" life. (See: [[rc://en/ta/man/translate/figs-metaphor]])