I started with this game around 6 months ago, earnings were much higher, the breeding was more popular so you could earn from breeding as much as from playing the game. ROI was in less than a month. Today is a different story, earnings are much less, many breeders stopped with breeding - so no additional income. AXS price skyrocketed since then and I don't think it will go much higher, so no point in buying AXS and wait to price jump, maybe just staking. ROI now is around 5 months which is big, because nobody knows what will happen with SLP price in the future if it will drop again or whatever. That being said, the safest way for new players is to find a scholarship, earn some money and decide later if they want to invest in their own team or no.
There is also a new option - farming RON coin, which will be used for transactions on the Ronin network. It is still not released, but will soon, we will see. And there are many other features in the game which will be available in the future like lands, upgrading axies parts etc.