Reading over the OP and I'm trying to fully grasp what I'm reading.
Right now I have a 401k with my employer and I'm contributing roughly 12% into it each paycheck (the company matches up to 6%). I'm trying to decide if it's wise to also open up a Roth IRA with Vanguard or is it better to buy a Vanguard Index Fund? I recently got a bonus from work for a couple grand that I wanted to just use towards one of those two. Just not sure what the better option would be.
The Vanguard index fund would be in your Vanguard Roth/traditional IRA. The Roth would be the account, and the index fund is what would be in the account.
Check out your 401K and see what you're invested in and what's available. It's possible your company has some good, low cost options and keeping it simple with your paycheck contribution is a good option. It's also possible your company has poor options and you only want to invest for the match. You can post the the fund options and expense ratios here and folks here can help guide you.
Out of curiousity, what's the benefit for active traders in this scenario?I'll point out one interesting concern he wrote. There is a chance that indexing doesn't work any more if active traders push for regulation on mutual funds / ETFs for restricting index funds to only one company per industry. That would certainly destroy indexing.