Ok, so let's say your rent is 1.2K. Over 3 years that's 43.2K. A 10% drop in a 250K house is only 25K, so you get a cheaper house but during the period of waiting you paid 43.2K in rent so that's 18.2K gone. You had to pay it anyway - but because it went to rent and not a mortgage you gain nothing. Saying 'it's a service' is meaningless we are talking about investment and as an investment it's money that doesn't buy you an asset = waste.
If you had bought earlier despite it being 10% more expensive you're putting that money into your house and in a position to build equity.
Finances aside what @IhateJan22 is probably referring to is that for many people especially FTB a home is not an investment it's a place to live. Apart from being able to do as you like, if you really wanted to calculate the costs and benefits like a real economist you'd factor in the risk of you rent rising, or being moved out of your house.
Especially in this era of LL's selling up. I know quite a few people whose deposits have been absolutely decimated by having to move multiple times in the space of two years. Just because OP has no issues with her current rental doesn't mean it'll stay that way forever.
Finally, you also have to factor in opportunity cost in calculating you profit - even if you sell at a loss after many years - what would the situation have been like if you'd paid rent instead, all those years?
All these factors need to be taken account and if you do, you realise there's' no clear answer. It depends on your personal risk assessment.. But when people talk about houses as an investment they only think about price, like you. 'Buy low sell high' makes sense for stocks but not houses, and using that as a comparison/guiding principle is naïve and ignores the complexities.
One thing I will say though negative equity is a real danger - which is why if possible don't overstretch yourself. If even the cheapest house is a stretch then maybe you have little choice but it's good to allow some room.
I don't know if it's as big of a risk these days - with 100% mortgages it was a very real possibility but the chances are lower with a double digit deposit (standard) also some can get 5% they're not a choice for everyone.