What should I do to help my best friend in university

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Once I have a very good friend in university and after graduation, we have keep in touch quite frequently when we are at the same city. But the last one year, he seldom contact with me and even not reply my message. Meanwhile, he has also stopped contact with other friends in university. I once asked him why, he said his working condition is not as good as expected, and it is a shame to contact with others whose life is much better than him, and once his life has become better, he would contact us again. I have tried to persuade him about giving up such kind of opinion but failed. What should I do about him?