Yes, you really need to weigh the pros and cons, especially your own personal risks. Things that may be higher risk to one person over another: kids’ school or extracurriculars, graduation of a loved one, weddings, health issues of yourself and loved ones, etc.
Cancelling is usually no. Rentals work best when you’re 100% committed to the trip.
Depending on the owner and rental, there may be a little bit of flexibility. They may allow one change but of course that risks not getting as good a resort/reservation since availability gets tighter as time goes on, and the date change would also need to be before those points expired.
Brokers and personal owners all have sightly different terms.
One rental I did the owner offered one date change and since they were using current UY points and were willing to bank to make one date change, I had 15 months after my initial to move my dates should something arise, if I did so before a certain date. And any change would need to be done at least 31 days out from our trip.
The times we rented DVC we knew were going come hell or high water lol. And we knew if something prevented that, we’d still eventually go. So not being able to cancel didn’t matter, but if flexibility was offered that gave us peace of mind that we could at least salvage a trip from the money laid out. Fortunately never needed to use it. For higher risk people, some of the brokers offer point insurance. Might be worth the extra costs if you’re not 99.9% sure and committed to your trip and dates.