There are a couple of observations that can be made about property purchasing in Last Will:
They don't get rid of as much money as you think. Sure, they cost a lot to buy, but the house is still an asset and part of your funds, and this is something you might be tempted to forget. Right up until you sell it and the money cascades back into your pile. If you spend the whole game focussing on just a couple of properties, you'll find that the total outlay isn't that much. Even with a fully favourable market, total decay, and an estate agent or two, you might only manage to sink 30 cash into a house at the most, and that's not a great return if you've spent a lot of turns on it (and nothing else; which brings me to my next point...).
Make sure you have a finishing strategy. If you learn only one thing from this answer, learn this. Properly done, houses can get rid of a lot of money, but it's actually impossible to get rid of ALL your money exclusively through property because you have to sell said property, which leaves you with a small pile of remaining money and no way left of efficiently spending it. I've seen games of Last Will in which a player has absolutely hosed his money away on properties, sold them at the end for a crippling loss, but has still been forced to crawl over the finish line because they're relying entirely on event cards and the "theatre" board action to get rid of their remaining pennies. Invariably another more balanced player will cross the line first (or at least go further into debt) because when it got to the end, they could still spend a decent amount with each action.
The most obvious player interaction is on the property market. There's very little interaction in the game. Actions on player's individual boards are totally independent. There's a little competition for good cards, or the wild-card companions, and there's competition for spaces in the turn order, but fundamentally, this does little except to change turn order for chasing the good cards. (If you don't care about turn order, there's pretty much always somewhere you can go that gets you close to what you want for cards/errands/actions balance.) But there's only one property market space, and it will affect everyone in the property business, and this can have a profound effect. The best time to dip into the property market will often be when most other people aren't interested. As always, you'll do better with no competition. Your opponent probably found that he could get decent helpers from the board (while everyone else fought over property-oriented cards) and largely play his own game, unconcerned with other players.
- Don't plough all your actions into maintaining properties and playing/activating helpers that only affect properties.
- Have an escape plan. Play a couple of helpers that work well together and will still be able to spend money once your properties are gone.
- As in all games, take the path of least resistance. Go for the strategy that the fewest other players are going for and you'll find less competition for the cards that suit that strategy.