How do you say §517君は確かにうまく行っているが、いつもそんな大儲けができる訳ではないから、それだけに頼るのは良くない。手遅れになる前に貯金をして、次の計画を立てておくのが望ましい。 in English?

You're doing well, to be sure, but it's not a good idea to rely completely on it, as it isn't always the case that you can make such a big profit. It's advisable that you should save and make your next plan before it is too late.