You seem to be asking, in essence, about term vs. whole-of-life (WOL) insurance. The major difference is that, since everyone dies, all WOL policies are guaranteed to pay out in the end, so the pricing of the premium is completely different.
For example, your $50pm premium may offer a payout of $1,500,000 in the event of your husband dying in the next 40 years (a very generous premium/payout ratio bearing in mind 80 is an above-average mortality age), but if you paid $50pm for WOL, you wouldn't expect to be covered for much more than $18,000 - $20,000 by the end of the term (($50 * 12) * 40 = $24,000 income for the insurer, calculated on an expected age at death of <= 80).
For WOL the numbers only make sense if the payout is very small compared to the premiums; for term they only make sense if the insurer can write lots and lots of policies that don't pay out, compared to only a few that do (to pay out one $1.5M term policy on a maximum of $24,000 income, the insurer would need ~62 other policies to not pay out just to break even on income/expense, without any margin for paying staff, admin costs, profits, offices, taxes and so on).
You can have tailored WOL policies that start out with a big payout while the insured is young but with that payout dropping as the insured ages - these are known in the industry (UK, anyway) as "reducing" or "decreasing" policies and are a reasonable compromise (for some definition of reasonable).
I don't ever offer advice (I'm not qualified) but I will say that as a note, the life reinsurance company I work for won't touch non-reducing, low-premium WOL policies (often known as "over 50 plans" in the UK) with a barge pole; the CEO believes they are a rip-off for the consumer, with no upside: if the policy is guaranteed to pay out then by definition, the average payout will always be less than the premiums paid, so you're better off saving/investing the premiums instead.
EDIT: to answer you last question directly:
So I am not understanding that what is the point of term life insurance? Are we betting that the person will die without the time period he/she has originally suggested.
You are betting that the insured will die before the end of the policy term; the underwriter is betting the insured won't.