If that's what you want, I'll save you some tokens:

#!/bin/sh

while read question; do echo "Put it into VFIAX"; done

There's quite a few implicit assumptions in that.

In my case, I am double-taxed (both Japan and US side) on capital gains. Tax treaties reduce, but not eliminate, the extent of double-taxation.

Many US-based brokers do not allow Americans abroad to purchase mutual funds, so VFIAX is not a choice for me.

Maybe I can go with eMAXIS Slim All Country... Oh, but that is a PFIC under IRS rules and I'd be taxed on unrealized capital gains. So I guess no Japan-equivalents of VT for me. That's fine, I guess I'll just buy VT in my US-based brokerage account; but now I'm in a suboptimal spot with respect to monthly contributions, calculating JPY-denominated income tax on dividends, etc.

I even made an implicit assumption when I said "calculating JPY-denominated income tax on dividends". That assumes your tax status is permanent resident. If your tax status NPR, then a decent financial advisor will recognize that only the extent of income remitted to Japan gets taxed, so VT distributing at all isn't an issue (until 5 years later). What do you before the 5 year threshold is hit? etc. etc.

But yes, if you're born in America and plan to stay within the same state for the rest of your life, then a 100% automated setup that simply deposits $1,000/mo into VFIAX is probably fine. (But keep in mind, to most non-Americans, the S&P 500 is not really diversified compared to funds like eMAXIS Slim All Country is).

Otherwise, there is value in consulting someone (or something) that regularly handles taxes and financial planning.

This is missing a lot of steps like:

- Building an emergency fund

- Budgeting and tracking where your money goes

- Planning and saving for large purchases like cars, homes and life goals

- Optimizing use of tax-advantaged accounts like 401Ks, HSAs, and IRAs

- What to do with ESPPs, RSUs, and options

- How taxes work and how to optimize around them

- Estate planning

While I also practice Bogle's approach from The Little Book of Common Sense Investing, even with this baseline there are some subtleties.

-VFIAX is currently $707/share. Fidelity's FXAIX does not have to be purchased in increments of a share price, and this fund's expenses are lower.

-There are versions of the S&P 500 for taxable accounts that minimize capital gains.

-Vanguard has a total-market index, VTSAX, that is mentioned in the book.

-Vanguard also has a non-U.S. total market fund, VTIAX, that avoid the current CAPE problems of the U.S. market.

Claude is very familiar with Bogle's approach, likely because the pirated book was part of the training set.

Some people do have complex financial situations. It's not as simple as that.

For example in the UK (and maybe US?) you get tax relief for money you put into your pensions, but there's a limit of £60k/year. Unless you earn a lot (which I do, yeay) when that limit is tapered. Except that you can also use up to 3 years of previously unused allowance. But you have to use this year's first.

Also interest is taxed, but you can put up to £20k/year into an ISA which isn't. And if you still want to avoid some tax you have kids ISA's and even pensions!

Then there are also startup investment schemes that save you some tax. Those seem to be not worth it, but you get the idea - it can be complicated. Especially if you are near one of the many tax/benefit thresholds.

The marginal tax rate in the UK bounces all over the place - it's even technically possible for it to be over 100%!