Build vs Buy

Spectrum

• All build — full in-house, custom.
• All buy — SaaS for everything.
• Hybrid — common reality.

Build when

• Differentiator capability (recommendation engine for e-commerce).
• Scale economics favor build.
• Have talent + budget for 3-5 year horizon.
• Unique requirement no vendor fits.

Buy when

• Commodity (BI, ETL).
• Speed-to-market critical.
• Talent constrained.
• Vendor ecosystem mature.

Hybrid example

• Buy warehouse (Snowflake), build dbt model in-house, buy BI (Looker), build ML platform in-house.

TCO consideration

• Build: license $0, but engineer cost + maintenance + opportunity cost.
• Buy: license $$, but faster + supported.
• Often build looks cheap year 1, expensive year 3+.

VN context

• Build muốn FTP cao — talent expensive.
• Buy USD pricing — FX risk.
• Hybrid is dominant pattern.

Decision framework

Anti-pattern

• "Not invented here" — build commodity to ego.
• Buy then customize 80% → costlier than build.