First, yes, a marketplace is really tough to approach as a bootstrapper. And, not especially appealing for investors.
As a personal example, with https://MastermindJam.com I effectively run a dating site.
Let me explain.
I set four strangers up on what amounts to a blind date into a peer-driven business mastermind group.
Much like eHarmony, I use around 30 points of data to make the best possible match that can be made with the candidates on hand.
Thus, the network effect, marketplace problem. These matching algorithms work fantastic when you're dealing with a large number of signups, but everything falls apart with a slow traffic month.
I might say that MastermindJam has a problem that's even more onerous than the one facing a dating site that matches people 1:1. I'm matching 4 people into groups. If one of these groups has a jerk in the mix, then the other three members walk away feeling they didn't get their money's worth and have a negative opinion of the service—for something that I have no control over.
(Because there's just no good way to ask people in a questionnaire if they're an asshat or not. Trust me, I've tried.)
So yeah, I can attest that bootstrapping a marketplace (or any business relying on network effect or matching humans with one another) is really, really difficult.
On to Rachel's second point...
I don't agree. I mean, yeah, this does happen, but it doesn't have to happen.
A great counterexample of Rachel's assertion would be the wedding-centric website https://www.theknot.com
The Knot helps you plan literally every aspect of your wedding. Seating charts, picking out groomsman outfits, invitations... everything!
And you'd think they lose a customer at the passing of every wedding date.
But not so.
After your wedding date, a clever sequence transitions you to their other properties:
The Nest https://www.thenest.com helps the newlyweds build a happy life together with advice, content, products, and services on housing, furnishings, cooking, budgeting, pets, and travel.
The Bump http://www.thebump.com Yes, you guessed it. After you're married, you've got the perfect home and personal life, many of The Knot customers will find baby advice useful at The Bump where they provide products and content around getting pregnant, fertility, pregnancy, newborns, infants, toddlers, kids, schooling, fashion and parenting.
Clearly, The Knot sees their customer differently. If they earned your trust in helping to plan a wedding, you're pretty likely to trust them in many of these other areas, too.
I think more dating sites should take that approach, frankly, but it requires a long-term vision most don't care for.
With a dating site, you could easily emulate the existing dating sites like OkCupid, and then after a successful match start offering services, content, and products to move them to engagement products, wedding products (divorce products ), and so forth.
But first, you have to have the guts and the strategy for solving the marketplace conundrum.
I'd love to hear more fresh ideas on how to defeat the marketplace dragon inherent in these matching services, personally. Is it absolutely a requirement to have a warchest of cash to throw at marketing, or are there other ways short of taking out a Super Bowl ad?