While the traditional quests lines in No Man Sky can yield you some much-needed cash. No Man Sky's economy system leaves a lot of room for making a profit. Within each star system, the price and scarcity of goods can wildly differ. And granted there are many ways to move around the galaxy. The Anomaly's stargate can provide access to other star systems without the need to Warp. Here is a few different options for buying and selling goods.
To aid you in your quest for richs. Here are a few ship upgrades to help increase your profits.
Inventory space is a be a big factor in how quickly you can move your trade goods. And while you can't purchase multiple ships when you don't have a freighter. Once you have one, purchasing ships while at Trade outposts and Space Stations will temporarily provide more space which you can access when your newly acquired ship has returned to your freighter.
Finally. There is a wealth of knowledge in the discovery and catalogue section of everything you've explored up to this point. It's worth taking a look.