I'm not one of the doomsdayers who is going to say Remember 2008? But remember 2008 ha ha.

I think projecting/expecting anywhere near 10% return is a mistake. You should be much more conservative in your planning so that you hit your mark. 5 or 6% return is more reasonable.

I think if you are far from retirement, stay the course and stick to your plan. As you get closer, things might change.

We’re on the cusp of retirement and what we’re experiencing is that we have a lot of pre tax savings. We plan on doing a lot of conversions to Roth to manage taxes.

Two quick thoughts:
1) Rather than looking at the expected return versus your contributions, look towards your ultimate goal. Even if expected returns are 10x your contributions, if you have a specific goal to retire at a certain age with a certain net worth, the contributions might be what gets you there on time. On the contrary, if you are way ahead of your savings goals, you can use that as barometer to start saving less.
2) IMO one of the most important things about saving money is simply not learning not to spend money. If you start spending an extra 100k on your lifestyle now, you will likely become accustomed to it and need it going forward, which will increase the total amount you need to retire comfortably.

I'm pretty old, and I've never known a time when the future felt more uncertain. My advice would be, keep saving and diversify for a number of possible outcomes.

Also don't underestimate the cost of maintaining a comfortable old age if/when illness or disability strike.

The historical average is 10 percent nominal, but 6.5 percent real (after adjusting for inflation). Past performance, etc.

https://www.investopedia.com/ask/answers/042415/what-average-annual-return-sp-500.asp

We have more than we need now and are well on track for retirement, but we don't know if we or our kids will fall ill or otherwise need expensive care, so saving more (without scrimping now) doesn't hurt. We will just have more to give to charity if we don't need it.

The past is not necessarily a good guide for the future, given everything that is going on.

That said, to answer your question, we will keep saving at our goal rate until retirement. We might increase spending a bit at the margins if our investments do better than expected, but they can always fall 40 percent tomorrow…

Is 10 percent on average even correct? I calculate whether our savings will be enough based on a 5 percent average. Would much rather discover I've got too much money than not enough one day.

Don't count your chickens before they're hatched.
You have yet to live through a 20% market correction or 40% recession like 2001 or 2008.
It gets scary then and you feel better with extra cushion.
If nothing goes wrong over the next 20 years (lol), then you can retire early

Treating yourself is not a bad idea -- just do it within reason.

It feels pointless when your saving is causing a situation where you're essentially starving yourself for a prolonged period just to gorge many years down the line.

Treat yourself to something this year to mark your success.

You need to find a smart way to invest in some alternatives and diversity your taxes down.
And not via a fund of funds or a FoF in vanguard. Or you do find one that takes $250k for early stage venture or a seed fund of funds.
Lock it up for 15 years and hope for a 5x net then, at 20% carried interest tax rates.

$5M NW and we keep throwing money into it. It's just an automatic reflex

10 percent on average feels way to high to bank on, pun intended. We have a net worth of more than $1.5m and are very eager to keep contributing to it.

We are able to save around 100k a year right now with current incomes and have a net worth of 1.5M. The stock market returns 10% on average, so avged out this 1.5M would grow by 150k on its own which is already more than we contribute every year. If had 5M, it would grow an average of 500k. This is 5x our contribution rate.

At some point doesn’t it kind of feel pointless put more money into your account unless your income keeps scaling with your net worth? TBH if we had 5M which isn’t quite enough to retire I might redirect that 100k of earned income into something else like a sports car or fancy vacations, and just let the 5M compound. At this level your growth is more about market performance and not 9-5 salary.

Obviously I know 10% is just a long term average and it doesn’t mean a steady 10% every year, some years it might be up or down by 20%+. But it’s averaged 10%.