You say it's enough for the majority in the world and you are probably right... ie china, india etc.
However in North America it would be a hard thing to feed a family and provide housing for 100k. I know in my area of the world you cannot rent an apartment for under 2k per month much less buy a car and make a living.
Shit - just my family credit card bills are around $10K CAD per month... Of course that doesn't include nearly all the monthly bills. Average home in Canada is around $500K, and in BC where I live, its $730K. It easily takes 6 figures to live here - which is why most families need both husband and wife to work.
I could consider moving someplace with a much lower cost of living - but I actually love living where I do. It's hot and sunny in the summer for pool & lake activities. Great biking most of the year, its fantastic skiing in the winter. Its beautiful views of mountains, valleys, orchards, etc... Sometimes there's a price to pay to be happy.
I've been lucky enough to not have a job since 1999 and my wife hasn't worked since 2000 when my daughter was born. I did web development for a few years which is what led me to understand domaining - which I really started in early 2004, focusing on .CA domains only and quickly weaned myself off of doing development work for other people. I have made lots of money domaining and lost lots of money trying to develop domains. So be careful if you're trying to develop. Don't just throw money at a project assuming it will pay off, and don't spend money you can't afford to lose. Also realize you can't do as good a job of domaining while trying to run another project either.
So if you want to make a living from domaining, there are two ways. 1) You broker or flip domains which means you never escape the daily grind. Or 2) You need to build a large quality portfolio and eventually sales cover your expenses and living.
If negotiating a sale, be sure you make plenty enough from any sale to in turn restock the portfolio with a much better domain or domains (so that you're always trading up). Re-invest EVERYTHING you can into the BEST domains you can buy. If you're working another job, live off that and don't pull money out of your domain business. You will also need to be willing to say no to very good offers to be able to make great (6-figure) sales. You'll never make a 6-figure sale if you keep accepting 4 or 5 figures - so know EVERYTHING you can about your buyer and know your domain (and the market for it). You might need to have a bank roll or line of credit to survive the slow years - there will be some. When things are good - pay for your renewals in advance a few years.
I don't do outbound sales, and I don't pre-price my domains. I quote every inquiry after researching the domain, the market, the buyer, etc... Keep track of all your inquiries, how you responded, what you quoted, what their offers were, etc... Review all past inquiries before you respond. If they try and negotiate price, offer them something other than a discount (like free financing i.e. payment plan, lease option, etc...). Never show weakness or sound desperate for a sale. Be friendly and helpful but just let them know the price isn't really negotiable - for some reason everyone thinks domainers are selling from a street cart in Morocco or something and that you gotta cut the price in half otherwise you lose the game. I feel that not being willing to negotiate much shows that you're _not_ a street vendor - and instead are a respectable business.
Don't be afraid to ask for high prices, sometimes that makes a domain look more valuable by pricing it high. Luxury goods are usually just over-priced stuff to show the world how rich you are. Domains aren't much different sometimes.
Here's an interesting example. I have a domain I owned for 14 years that gets at LEAST one serious inquiry a week, many from existing businesses using a similar longer 2-word domain, some are startups. Over those years, I was originally asking $50K. Then I bumped it to $100K. Then I bumped it to $150K. Then I bumped it to $200K. Now it just sold. Counter-intuitive, right? Now I've got another well funded startup asking me to bail on the current deal because they'll make it worth my time. Unfortunately - I can't because I have a counter-signed contract - just waiting on payment. So I'm pricing my best domains higher and higher and having success. It's worth the wait. The reality is, the big companies who want your domain are willing to pay big money. Don't be afraid to ask for it, don't be willing to take less if you don't have to.
That's how I've made a living from it.