A typical "friend who wants to help them with investing" is actually out for himself.
The most benign way this occurs is the "friend" recommends them into annuities and load mutual funds that pay him a gigantic commission, at the expense of the value of the investment.
For instance I found a Florida investment "counselor" had put my parents into a bunch of "A" class mutual funds (meaning there is a 5.75% front-end load to enter the fund; invest $100,000 and only $94k actually posts to the fund; you hope it grows normally after that but they are also paying the funds manager 1.19% per year, which is guaranteed pure loss.
The manager is simply buying large-caps; you could accomplish the same end by buying VFINX, which invests in all large-cap stocks, has a 0% front-end load and 0.08% annual fees. Supposedly the manager picks better stocks than VFINX; but he'd have to pick them 1.11% better or it's a net lose. Statistics say he's not that much better.
A typical strategy for these commission chasers is to put you into ridiculously complex investments, like variable annuities, where nobody but a few "smartest guy in the room types" on Wall Street even know what they are doing internally. This is part of a greater scam, where they try to convince the public that investment is oh, so complicated and therefore you need their help. No, it isn't! The nut of investing, the part that makes the money, is easy. Suze Orman teaches it. University endowments do as well as humanly possible and they keep it simple. It's all the jacked-up complications they add to rip you off, those are complicated.
That's the littlest ripoff.
It's also possible that this "friend" is going to do something even worse. And there's lots and lots of worse, which looks like "take the money and run".
Why are you investing anyway?
Assuming a lifespan of 90, this is awfully late in the game to be investing. This is the time when prudent investors have phased almost fully out of stocks and other high-growth high-volatility investments. It's the volatility that's the problem. If you plan to redeem the money in 30 years (e.g. Your kids' IRA), go all-in to the stock market - it always performs well over 30 years. But if you need the money in 5-10 years, that's when you get nailed by the volatility. You can actually lose money over 10 years, and you can lose most of your money over 5 years, if the market does the wrong thing in those 5 years. Imagine you bought in 1928 and sold in 1933. Bought in 2003 and sold in 2008. Those are just the famous ones I can recall off the top of my head.
And lots of people believe the market is at peak right now. It can only go down from here. No, perhaps if Wall Street was having a "half off" sale like in 2008, but right now? Not even stupid given their short window of time.
No, giving that your parents are actively using their savings, it should not be invested in the stock market. Reliable bonds, maybe; but your "friend" will not be interested in putting them in such low-risk low-profit investments, because then the commission losses/ripoff will be obvious.
Their idea to downsize is a good idea
The biggest problem people get into at that age is "too much house to maintain". This can turn into loss of value of the home for lack of maintenance, and even living in squalor - I know a 75 year old who simply went out in his garden and dug a hole, because his toilet broke and he was stuck on fixing it. This happens.
So downsizing is a good idea.
Another good idea is an independent living center, which is a set of condos specifically for independent seniors. Typically they buy in with the equity in their home, and pay most of their Social Security as maintenance fees. They keep their car (but the site is usually set up so you could get by without one), and there is typically a restaurant on-site they can eat anytime. This is still "normal adult living", but not having to mow a lawn anymore or fix a water heater.
Even better is when the independent living center also has a wing for assisted living, which is the next step... Or a skilled nursing facility, which is the last step before hospice. Some of them will even insure your steps, by guaranteeing you a slot for life in whichever facility you need. My parents have that, and they joined at about your parent's age.
One would not go straight from living in ones own home to a SNF, unless one had a sudden health issue.