15 Angel Investing Mistakes That Cost Me Millions

Published 2026-04-28 · Updated 2026-05-23 · · Angel Investing · By Sahin Boydas

The most expensive mistakes I've made across 207+ angel investments. Pattern recognition for avoiding common pitfalls.

Angel Investing Mistakes: 15 Costly Errors I've Made (And How to Avoid Them)

The most expensive mistakes I've made across 207+ angel investments. FOMO deals, valuation traps, and the errors that cost me the most.

Written by Sahin Boydas — serial entrepreneur, 2x exited founder, and angel investor in 207+ startups including OpenAI, Anthropic, Scale AI, and Hugging Face. Ranked #1 most active angel investor in 2024 by Crunchbase.

This article is part of my ongoing series on angel investing, based on real experience from building a portfolio of 207+ investments across AI, fintech, robotics, developer tools, and more.

For more insights on startup investing, visit my blog or follow me on Twitter.

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