IMHO the hard part with a startup is you don't want to build something that works sustainably at scale. You want to build something that could plausibly morph into something that is sustainable at scale.
I've started to look at scaling like you're killing a golden-egg-laying goose but there's a 1 in n chance that it'll pay off for you. n starts higher than you'd hope and rises as you make tradeoffs.
I've been thinking about scaling a bit because I've been digging into a large SaaS product for a client and find I am able to replicate their locally relevant output at a fraction of the cost. Scaling up has allowed this SaaS to serve an entire country but a majority of their user base think in terms of one or two local counties. Consuming their output means subsidizing work they do that's irrelevant to (or might actually compete with) your own interests.
