wat?
That is a risky game just for £96 over 18 months.
How does making £96 in interest enable you to own another rental property?
It is only risky if you spend more than you can afford and in that case I agree you should not have a credit card for anything other than emergencies.
The interest does not help me buy a house, I was illustrating that it is possible to have debt and make more money vs not having debt and pointing out that someone with a logical mind would min/max the system to get the maximum benefits from it. £96 might not be a lot of money but it is better than £0 and it is a lot better than paying interest.
What does help me buy the house though is the capital I still have. I could pay off the debt and lose that capital or I could add to it with other savings and buy an asset that would cover the interest cost of the credit card in the instance that I can not shift the debt to another 0% deal again. By not paying off the debt but using the capital I come out ahead compared to paying off the debt.
This cannot go on for ever though but it both gives me time and helps me be in a stronger financial position when I decide to pay off the debt. There is also a ceiling point where it stops you from getting mortgages but that depends on the amount of income you have so if you use the debt to increase earnings you can stretch it pretty far.
:This bit is a bit off topic but it illustrates a point about debt vs no debt and how debt can be used to your advantage if you manage it properly:
If I had £1,000,000 I could buy 10 £100,000 houses to rent out. I could earn around £600pcm/house so I would have a profit of £6,000 pcm and no debt.
I could also buy 40 houses with 25% deposits. The interest would be around £375pcm @5.99% (quite high even for a buy to let) per house.
Total interest = £15,000pcm
Total income = £24,000pcm
Total profit = £9,000pcm and debt
By being in debt I am better off by £3,000 a month which is a lot more than the debt free route. This is very simplistic but I used a high interest rate so it is around the ball park. The other advantage is that my risk is spread out among more properties so losing a tenant has less impact in the second scenario than the first.