Building a Vertical Integrator is really hard. 

1. >2 companies at once
2. Hardware is really hard
3. Incumbents are not dumb
4. The right level of integration is not obvious
5. Can’t pivot nearly as easily
6. Something better might come along
7. Takes money to make money

Vertical integration requires careful planning and substantial resources. It's a complex process with many challenges to consider, from managing multiple companies to dealing with technological hurdles. Success demands a strategic approach and a long-term vision to overcome obstacles and stay competitive in the market.