We own many timeshares. Some were purchased in the early 1990's when I knew very little about timesharing. Then along came TUG and through the years I learned a lot.
I won't repeat many of the great comments made above but will just add a few other random tidbits that I think may not have been covered.
Many of the the repeat customers from the New York-New Jersey area who rented our February timeshare weeks in Ft. Lauderdale and Pompano Beach, Florida for years eventually retired to Florida and bought full year or half year condos. So they, and their children and grandchildren, have no need to rent timeshares anymore.
Many long-time owners are now seniors who no longer crave vacations. As retirees, everyday is a vacation. No need to escape job pressures to unwind. Even if their health is good (a big IF as the years go by) and they have not lost their spouse/aka favorite traveling companion, they've "been there, done that" re: exchanges. So they just give away their timeshares to family members, friends, the resort, or strangers for free.
Resorts are aging too, and climate seems to be more extreme. So maintenance fees keep rising and large Special Assessments are sometimes needed to keep the resort afloat. Look at the recent TUG thread about the Diamond Resort Hawaii timeshare property that is billing the owners a $5,000. assessment
Due to the serious economic situation, I see lots of people cutting back on optional leisure expenses even when they are in good financial shape.
Airline travel has become more difficult--long lines, increasing fares, delayed or canceled flights, shoe removal, no room in the overhead bins, etc...
Young people coming out of high school and college are not finding jobs easily, especially ones that pay a decent salary. So they too are holding tight to their wallets and not splurging on non-necessities such as vacations, nor are their parents treating them to vacations. Some analysts fear that the younger generation may be developing a "Depression era" mentality that will make them extremely frugal for years to come.
Oh, and then what happens if we have a major terror attack.
Things are changing, and unfortunately not for the better.
And leave it to greedy RCI and it's many subsideraries to undercut your efforts to even cover your maintenance fees. They "steal" deposited weeks and rent them to the general public at prices below what the owner pays in maintenance fees.
That said, we do own several weeks that we enjoy using every year. They would (and have) rented easily at a good, not great, profit when we chose not to go. But a huge hurrican could put them out of commission for years as happened with the Wyndham Santa Barbara resort in Pompano Beach a few years back, and to a few buildings at the Wyndham Sea Gardens Resort.
I wish we did not own some of our weeks. Many were wonderful for years. But things change.
Overall, I think the risk/reward ratio for renting at a profit is not favorable in these times--and maybe never.