Surely that very much depends on whether your product fits within the current or near future offering of Azure/AWS.
The other side of that coin is that you use a build horizontal integration strategy to replace elements of the products you buy from Azure/AWS if (and only if) it can be done in a way that increase your profit/value.
It can work both ways. Moving from buy to build also has elements of de-risking and economies of scale if you do it at the point where there is measurable success/product to market fit.
Building something you can buy too early runs the risk of premature optimisation if not done for the right reasons.
The other side of that coin is that you use a build horizontal integration strategy to replace elements of the products you buy from Azure/AWS if (and only if) it can be done in a way that increase your profit/value.
It can work both ways. Moving from buy to build also has elements of de-risking and economies of scale if you do it at the point where there is measurable success/product to market fit.
Building something you can buy too early runs the risk of premature optimisation if not done for the right reasons.