SS is a solo dev project, even if you were to throw a billion dollars at Alex, the game wouldn't get made any faster - it's his full-time job working on the game and wrangling this forum. He could buy more spritework time from david, or even contributions from other artists - but from what I understand artwork isn't a bottleneck on content (especially seeing as programmer art is good enough to do quick and dirty tests for functionality).
Having to go through your codebase and hook in appropriate calls and methodology whenever you create/replace a piece of the game is what takes a ton of devwork (and then making sure it's not throwing bugs, causing the game to choke by waiting for input at the wrong time, etc). As in the most recent update of getting story missions implemented, as it required touching so many aspects.
Basically, making games is way harder than you seem to think - which is why there's no cheap clone of SS's gameplay on the app store, because it would require actual development time to copy, not the only bottleneck being how many art assets you can crudely trace over and implement like most mobile gachas.
