Did you check the price of a first class ticket?
Yes, a first class ticket can cost between $7K-$10K for NYC-TLV RT or 5,000 points + around $350 in fuel charges. Which is why it is usually cheaper to get an F bonus ticket on El Al than a paid ticket.
BUT - there's a well known secret that you can buy 100% of the points you're missing for a ticket at $1 per point which makes a paid F ticket come out to ~$5,350 in cash. The only difference between a ticket purchased with points (even if it's through purchased points) as upposed to cash is that this ticket won't EARN more points + it doesn't include a driver to take you back and forth from the airport.
I think you will find that it is easier to earn $5,000 in cash backs than it is to earn 5,000 El Al points. Plus assuming you want SOME flexibility and don't want to be locked in to just utilizing for F (other classes can be less cost effective in points than in cash + availability is a painful issue), you're way way better off with cash.
I have around 7,000 LY points and have been trying to get a C ticket for June for the past few weeks and am on endless waiting lists. I would much prefer to be sitting on $7,000 in cash and purchase the tickets (I would have probably had much more than $7,000 with the right cash back card for the same spend that got me the 7,000 points). Again, unlike F, tickets in Y and C are usually cheaper in $ than in points + fuel (when you consider each point $1).