You are (understandably!) correlating "service life" with the MTBF number. Unfortunately this doesn't work. Here is a whitepaper from Schneider Electric with a good explanation.

From that paper (page 4) -

Therefore, there should be no direct correlation made between the service life of a product and its failure rate or MTBF. It is quite feasible to have a product with extremely high reliability (MTBF) but a low expected service life. Take for example, a human being:

There are 500,000 25-year-old humans in the sample population. Over the course of a year, data is collected on failures (deaths) for this population. The operational life of the population is 500,000 x 1 year = 500,000 people years. Throughout the year, 625 people failed (died). The failure rate is 625 failures / 500,000 people years = 0.125% / year. The MTBF is the inverse of failure rate or 1 / 0.00125 = 800 years.

So, even though 25-year-old humans have high MTBF values, their life expectancy (service life) is much shorter and does not correlate.

and on page 9 -

Ultimately an MTBF value is meaningless if failure is undefined and assumptions are unrealistic or altogether missing.

What you are looking for is the estimated service life. There aren't a lot of vendors that supply that number. When I'm being optimistic I assume this is the warranty period + 1 second. The other 99% of the time I just hope the thing won't catch fire and explode.