One estimate I have seen is $1 to $2 million USD, which I think is too low [1]. I would estimate it at at $7 to $14 million USD.

Here's the back-of-the-envelope calculation I used to come up with this number: Annual salary: $250K. Assume 25% tax, which leaves us with $187.5K, which is about $15K per month. Assume $5000 in monthly expenses, which leaves us with $10K per month investable money. (Note: since net worth includes house and 401(k) I have not deducted mortgage or 401(k) payments). So $10K includes those items.) Now use a compound interest calculator [2] to see what $10K per month at 8% interest (assume investment in S&P 500 and allow for some market crashes) will result in, at the end of 30 years. It is about $14 million, which would include your house and your 401(k).

[1] https://www.quora.com/What-is-a-good-software-engineer%E2%80%99s-e-g-working-at-Google-etc-usual-net-worth-by-the-age-of-55 [2] https://www.investor.gov/additional-resources/free-financial-planning-tools/compound-interest-calculator