A common tactic people mistakenly do: tip of the sphere

The "tip of the spear" playbook works to get a maximally scoped down toehold to then incrementally invest in.

Key to it is the tip of the spear is sharp and a small scope.

A smaller scope is super-linearly easier to coordinate to build than a larger scope.

The tip of the sphere playbook is when you accidentally allow the scope to creep up significantly.

It's easy to add new requirements, hard to take them away.

The spear turns into a sphere slowly without people noticing, and before you know it you have a massive investment of energy before the thing gets to viability… which makes it more likely it never achieves viability.