I suppose the business background of EGCTV helps. Unlike aoe2 folks who are mostly streamers-turned organisers, he actually seems to be a successful PR/business guy on his own. At least he can afford spending 10k on aoe3 and even more on aoe4 out of his pocket
I think it's simply a case of egc guy has some spare cash which he is willing to use as he pleases. There is no clear upside on investing so much in aoe4 with how player base keeps on declining
And money attracts money, if you already have 50k from your own pocket then finding another 10-20k is lot easier as opposed to having zero own investment